18
Python is an interpreted, interactive, object-oriented programming language. It
19
incorporates modules, exceptions, dynamic typing, very high level dynamic data
20
types, and classes. Python combines remarkable power with very clear syntax.
21
It has interfaces to many system calls and libraries, as well as to various
22
window systems, and is extensible in C or C++. It is also usable as an
23
extension language for applications that need a programmable interface.
24
Finally, Python is portable: it runs on many Unix variants, on the Mac, and on
25
Windows 2000 and later.
27
To find out more, start with :ref:`tutorial-index`. The `Beginner's Guide to
28
Python <https://wiki.python.org/moin/BeginnersGuide>`_ links to other
29
introductory tutorials and resources for learning Python.
32
What is the Python Software Foundation?
33
---------------------------------------
35
The Python Software Foundation is an independent non-profit organization that
36
holds the copyright on Python versions 2.1 and newer. The PSF's mission is to
37
advance open source technology related to the Python programming language and to
38
publicize the use of Python. The PSF's home page is at
39
https://www.python.org/psf/.
41
Donations to the PSF are tax-exempt in the US. If you use Python and find it
42
helpful, please contribute via `the PSF donation page
43
<https://www.python.org/psf/donations/>`_.
46
Are there copyright restrictions on the use of Python?
47
------------------------------------------------------
49
You can do anything you want with the source, as long as you leave the
50
copyrights in and display those copyrights in any documentation about Python
51
that you produce. If you honor the copyright rules, it's OK to use Python for
52
commercial use, to sell copies of Python in source or binary form (modified or
53
unmodified), or to sell products that incorporate Python in some form. We would
54
still like to know about all commercial use of Python, of course.
56
See `the PSF license page <https://www.python.org/psf/license/>`_ to find further
57
explanations and a link to the full text of the license.
59
The Python logo is trademarked, and in certain cases permission is required to
60
use it. Consult `the Trademark Usage Policy
61
<https://www.python.org/psf/trademarks/>`__ for more information.
64
Why was Python created in the first place?
65
------------------------------------------
67
Here's a *very* brief summary of what started it all, written by Guido van
70
I had extensive experience with implementing an interpreted language in the
71
ABC group at CWI, and from working with this group I had learned a lot about
72
language design. This is the origin of many Python features, including the
73
use of indentation for statement grouping and the inclusion of
74
very-high-level data types (although the details are all different in
77
I had a number of gripes about the ABC language, but also liked many of its
78
features. It was impossible to extend the ABC language (or its
79
implementation) to remedy my complaints -- in fact its lack of extensibility
80
was one of its biggest problems. I had some experience with using Modula-2+
81
and talked with the designers of Modula-3 and read the Modula-3 report.
82
Modula-3 is the origin of the syntax and semantics used for exceptions, and
83
some other Python features.
85
I was working in the Amoeba distributed operating system group at CWI. We
86
needed a better way to do system administration than by writing either C
87
programs or Bourne shell scripts, since Amoeba had its own system call
88
interface which wasn't easily accessible from the Bourne shell. My
89
experience with error handling in Amoeba made me acutely aware of the
90
importance of exceptions as a programming language feature.
92
It occurred to me that a scripting language with a syntax like ABC but with
93
access to the Amoeba system calls would fill the need. I realized that it
94
would be foolish to write an Amoeba-specific language, so I decided that I
95
needed a language that was generally extensible.
97
During the 1989 Christmas holidays, I had a lot of time on my hand, so I
98
decided to give it a try. During the next year, while still mostly working
99
on it in my own time, Python was used in the Amoeba project with increasing
100
success, and the feedback from colleagues made me add many early
103
In February 1991, after just over a year of development, I decided to post to
104
USENET. The rest is in the ``Misc/HISTORY`` file.
107
What is Python good for?
108
------------------------
110
Python is a high-level general-purpose programming language that can be applied
111
to many different classes of problems.
113
The language comes with a large standard library that covers areas such as
114
string processing (regular expressions, Unicode, calculating differences between
115
files), Internet protocols (HTTP, FTP, SMTP, XML-RPC, POP, IMAP, CGI
116
programming), software engineering (unit testing, logging, profiling, parsing
117
Python code), and operating system interfaces (system calls, filesystems, TCP/IP
118
sockets). Look at the table of contents for :ref:`library-index` to get an idea
119
of what's available. A wide variety of third-party extensions are also
120
available. Consult `the Python Package Index <https://pypi.python.org/pypi>`_ to
121
find packages of interest to you.
124
How does the Python version numbering scheme work?
125
--------------------------------------------------
127
Python versions are numbered A.B.C or A.B. A is the major version number -- it
128
is only incremented for really major changes in the language. B is the minor
129
version number, incremented for less earth-shattering changes. C is the
130
micro-level -- it is incremented for each bugfix release. See :pep:`6` for more
131
information about bugfix releases.
133
Not all releases are bugfix releases. In the run-up to a new major release, a
134
series of development releases are made, denoted as alpha, beta, or release
135
candidate. Alphas are early releases in which interfaces aren't yet finalized;
136
it's not unexpected to see an interface change between two alpha releases.
137
Betas are more stable, preserving existing interfaces but possibly adding new
138
modules, and release candidates are frozen, making no changes except as needed
139
to fix critical bugs.
141
Alpha, beta and release candidate versions have an additional suffix. The
142
suffix for an alpha version is "aN" for some small number N, the suffix for a
143
beta version is "bN" for some small number N, and the suffix for a release
144
candidate version is "cN" for some small number N. In other words, all versions
145
labeled 2.0aN precede the versions labeled 2.0bN, which precede versions labeled
146
2.0cN, and *those* precede 2.0.
148
You may also find version numbers with a "+" suffix, e.g. "2.2+". These are
149
unreleased versions, built directly from the Subversion trunk. In practice,
150
after a final minor release is made, the Subversion trunk is incremented to the
151
next minor version, which becomes the "a0" version,
154
See also the documentation for :data:`sys.version`, :data:`sys.hexversion`, and
155
:data:`sys.version_info`.
158
How do I obtain a copy of the Python source?
159
--------------------------------------------
161
The latest Python source distribution is always available from python.org, at
162
https://www.python.org/download/. The latest development sources can be obtained
163
via anonymous Mercurial access at https://hg.python.org/cpython.
165
The source distribution is a gzipped tar file containing the complete C source,
166
Sphinx-formatted documentation, Python library modules, example programs, and
167
several useful pieces of freely distributable software. The source will compile
168
and run out of the box on most UNIX platforms.
170
Consult the `Getting Started section of the Python Developer's Guide
171
<https://docs.python.org/devguide/setup.html>`__ for more
172
information on getting the source code and compiling it.
175
How do I get documentation on Python?
176
-------------------------------------
180
The standard documentation for the current stable version of Python is available
181
at https://docs.python.org/3/. PDF, plain text, and downloadable HTML versions are
182
also available at https://docs.python.org/3/download.html.
184
The documentation is written in reStructuredText and processed by `the Sphinx
185
documentation tool <http://sphinx-doc.org/>`__. The reStructuredText source for
186
the documentation is part of the Python source distribution.
189
I've never programmed before. Is there a Python tutorial?
190
---------------------------------------------------------
192
There are numerous tutorials and books available. The standard documentation
193
includes :ref:`tutorial-index`.
195
Consult `the Beginner's Guide <https://wiki.python.org/moin/BeginnersGuide>`_ to
196
find information for beginning Python programmers, including lists of tutorials.
199
Is there a newsgroup or mailing list devoted to Python?
200
-------------------------------------------------------
202
There is a newsgroup, :newsgroup:`comp.lang.python`, and a mailing list,
203
`python-list <https://mail.python.org/mailman/listinfo/python-list>`_. The
204
newsgroup and mailing list are gatewayed into each other -- if you can read news
205
it's unnecessary to subscribe to the mailing list.
206
:newsgroup:`comp.lang.python` is high-traffic, receiving hundreds of postings
207
every day, and Usenet readers are often more able to cope with this volume.
209
Announcements of new software releases and events can be found in
210
comp.lang.python.announce, a low-traffic moderated list that receives about five
211
postings per day. It's available as `the python-announce mailing list
212
<https://mail.python.org/mailman/listinfo/python-announce-list>`_.
214
More info about other mailing lists and newsgroups
215
can be found at https://www.python.org/community/lists/.
218
How do I get a beta test version of Python?
219
-------------------------------------------
221
Alpha and beta releases are available from https://www.python.org/download/. All
222
releases are announced on the comp.lang.python and comp.lang.python.announce
223
newsgroups and on the Python home page at https://www.python.org/; an RSS feed of
226
You can also access the development version of Python through Mercurial. See
227
https://docs.python.org/devguide/faq.html for details.
230
How do I submit bug reports and patches for Python?
231
---------------------------------------------------
233
To report a bug or submit a patch, please use the Roundup installation at
234
https://bugs.python.org/.
236
You must have a Roundup account to report bugs; this makes it possible for us to
237
contact you if we have follow-up questions. It will also enable Roundup to send
238
you updates as we act on your bug. If you had previously used SourceForge to
239
report bugs to Python, you can obtain your Roundup password through Roundup's
240
`password reset procedure <https://bugs.python.org/user?@template=forgotten>`_.
242
For more information on how Python is developed, consult `the Python Developer's
243
Guide <https://docs.python.org/devguide/>`_.
246
Are there any published articles about Python that I can reference?
247
-------------------------------------------------------------------
249
It's probably best to cite your favorite book about Python.
251
The very first article about Python was written in 1991 and is now quite
254
Guido van Rossum and Jelke de Boer, "Interactively Testing Remote Servers
255
Using the Python Programming Language", CWI Quarterly, Volume 4, Issue 4
256
(December 1991), Amsterdam, pp 283-303.
259
Are there any books on Python?
260
------------------------------
262
Yes, there are many, and more are being published. See the python.org wiki at
263
https://wiki.python.org/moin/PythonBooks for a list.
265
You can also search online bookstores for "Python" and filter out the Monty
266
Python references; or perhaps search for "Python" and "language".
269
Where in the world is www.python.org located?
270
---------------------------------------------
272
The Python project's infrastructure is located all over the world.
273
`www.python.org <https://www.python.org>`_ is graciously hosted by `Rackspace
274
<http://www.rackspace.com>`_, with CDN caching provided by `Fastly
275
<https://www.fastly.com>`_. `Upfront Systems
276
<http://www.upfrontsystems.co.za>`_ hosts `bugs.python.org
277
<https://bugs.python.org>`_. Many other Python services like `the Wiki
278
<https://wiki.python.org>`_ are hosted by `Oregon State
279
University Open Source Lab <https://osuosl.org>`_.
282
Why is it called Python?
283
------------------------
285
When he began implementing Python, Guido van Rossum was also reading the
286
published scripts from `"Monty Python's Flying Circus"
287
<http://en.wikipedia.org/wiki/Monty_Python>`__, a BBC comedy series from the 1970s. Van Rossum
288
thought he needed a name that was short, unique, and slightly mysterious, so he
289
decided to call the language Python.
292
Do I have to like "Monty Python's Flying Circus"?
293
-------------------------------------------------
298
Python in the real world
299
========================
301
How stable is Python?
302
---------------------
304
Very stable. New, stable releases have been coming out roughly every 6 to 18
305
months since 1991, and this seems likely to continue. Currently there are
306
usually around 18 months between major releases.
308
The developers issue "bugfix" releases of older versions, so the stability of
309
existing releases gradually improves. Bugfix releases, indicated by a third
310
component of the version number (e.g. 2.5.3, 2.6.2), are managed for stability;
311
only fixes for known problems are included in a bugfix release, and it's
312
guaranteed that interfaces will remain the same throughout a series of bugfix
315
The latest stable releases can always be found on the `Python download page
316
<https://www.python.org/download/>`_. There are two recommended production-ready
317
versions at this point in time, because at the moment there are two branches of
318
stable releases: 2.x and 3.x. Python 3.x may be less useful than 2.x, since
319
currently there is more third party software available for Python 2 than for
320
Python 3. Python 2 code will generally not run unchanged in Python 3.
323
How many people are using Python?
324
---------------------------------
326
There are probably tens of thousands of users, though it's difficult to obtain
329
Python is available for free download, so there are no sales figures, and it's
330
available from many different sites and packaged with many Linux distributions,
331
so download statistics don't tell the whole story either.
333
The comp.lang.python newsgroup is very active, but not all Python users post to
334
the group or even read it.
337
Have any significant projects been done in Python?
338
--------------------------------------------------
340
See https://www.python.org/about/success for a list of projects that use Python.
341
Consulting the proceedings for `past Python conferences
342
<https://www.python.org/community/workshops/>`_ will reveal contributions from many
343
different companies and organizations.
345
High-profile Python projects include `the Mailman mailing list manager
346
<http://www.list.org>`_ and `the Zope application server
347
<http://www.zope.org>`_. Several Linux distributions, most notably `Red Hat
348
<http://www.redhat.com>`_, have written part or all of their installer and
349
system administration software in Python. Companies that use Python internally
350
include Google, Yahoo, and Lucasfilm Ltd.
353
What new developments are expected for Python in the future?
354
------------------------------------------------------------
356
See https://www.python.org/dev/peps/ for the Python Enhancement Proposals
357
(PEPs). PEPs are design documents describing a suggested new feature for Python,
358
providing a concise technical specification and a rationale. Look for a PEP
359
titled "Python X.Y Release Schedule", where X.Y is a version that hasn't been
360
publicly released yet.
362
New development is discussed on `the python-dev mailing list
363
<https://mail.python.org/mailman/listinfo/python-dev/>`_.
366
Is it reasonable to propose incompatible changes to Python?
367
-----------------------------------------------------------
369
In general, no. There are already millions of lines of Python code around the
370
world, so any change in the language that invalidates more than a very small
371
fraction of existing programs has to be frowned upon. Even if you can provide a
372
conversion program, there's still the problem of updating all documentation;
373
many books have been written about Python, and we don't want to invalidate them
374
all at a single stroke.
376
Providing a gradual upgrade path is necessary if a feature has to be changed.
377
:pep:`5` describes the procedure followed for introducing backward-incompatible
378
changes while minimizing disruption for users.
381
Is Python a good language for beginning programmers?
382
----------------------------------------------------
386
It is still common to start students with a procedural and statically typed
387
language such as Pascal, C, or a subset of C++ or Java. Students may be better
388
served by learning Python as their first language. Python has a very simple and
389
consistent syntax and a large standard library and, most importantly, using
390
Python in a beginning programming course lets students concentrate on important
391
programming skills such as problem decomposition and data type design. With
392
Python, students can be quickly introduced to basic concepts such as loops and
393
procedures. They can probably even work with user-defined objects in their very
396
For a student who has never programmed before, using a statically typed language
397
seems unnatural. It presents additional complexity that the student must master
398
and slows the pace of the course. The students are trying to learn to think
399
like a computer, decompose problems, design consistent interfaces, and
400
encapsulate data. While learning to use a statically typed language is
401
important in the long term, it is not necessarily the best topic to address in
402
the students' first programming course.
404
Many other aspects of Python make it a good first language. Like Java, Python
405
has a large standard library so that students can be assigned programming
406
projects very early in the course that *do* something. Assignments aren't
407
restricted to the standard four-function calculator and check balancing
408
programs. By using the standard library, students can gain the satisfaction of
409
working on realistic applications as they learn the fundamentals of programming.
410
Using the standard library also teaches students about code reuse. Third-party
411
modules such as PyGame are also helpful in extending the students' reach.
413
Python's interactive interpreter enables students to test language features
414
while they're programming. They can keep a window with the interpreter running
415
while they enter their program's source in another window. If they can't
416
remember the methods for a list, they can do something like this::
419
>>> dir(L) # doctest: +NORMALIZE_WHITESPACE
420
['__add__', '__class__', '__contains__', '__delattr__', '__delitem__',
421
'__dir__', '__doc__', '__eq__', '__format__', '__ge__',
422
'__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__',
423
'__imul__', '__init__', '__iter__', '__le__', '__len__', '__lt__',
424
'__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__',
425
'__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__',
426
'__sizeof__', '__str__', '__subclasshook__', 'append', 'clear',
427
'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove',
429
>>> [d for d in dir(L) if '__' not in d]
430
['append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']
433
Help on built-in function append:
436
L.append(object) -> None -- append object to end
442
With the interpreter, documentation is never far from the student as he's
445
There are also good IDEs for Python. IDLE is a cross-platform IDE for Python
446
that is written in Python using Tkinter. PythonWin is a Windows-specific IDE.
447
Emacs users will be happy to know that there is a very good Python mode for
448
Emacs. All of these programming environments provide syntax highlighting,
449
auto-indenting, and access to the interactive interpreter while coding. Consult
450
`the Python wiki <https://wiki.python.org/moin/PythonEditors>`_ for a full list
451
of Python editing environments.
453
If you want to discuss Python's use in education, you may be interested in
454
joining `the edu-sig mailing list
455
<https://www.python.org/community/sigs/current/edu-sig>`_.
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