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Python is an interpreted, interactive, object-oriented programming language. It incorporates modules, exceptions, dynamic typing, very high level dynamic data types, and classes. Python combines remarkable power with very clear syntax. It has interfaces to many system calls and libraries, as well as to various window systems, and is extensible in C or C++. It is also usable as an extension language for applications that need a programmable interface. Finally, Python is portable: it runs on many Unix variants, on the Mac, and on Windows 2000 and later.
To find out more, start with :ref:`tutorial-index`. The What is the Python Software Foundation?
The Python Software Foundation is an independent non-profit organization that holds the copyright on Python versions 2.1 and newer. The PSF's mission is to advance open source technology related to the Python programming language and to publicize the use of Python. The PSF's home page is at the PSF donation page.
You can do anything you want with the source, as long as you leave the copyrights in and display those copyrights in any documentation about Python that you produce. If you honor the copyright rules, it's OK to use Python for commercial use, to sell copies of Python in source or binary form (modified or unmodified), or to sell products that incorporate Python in some form. We would still like to know about all commercial use of Python, of course.
See the Trademark Usage Policy for more information.
Here's a very brief summary of what started it all, written by Guido van Rossum:
I had extensive experience with implementing an interpreted language in the ABC group at CWI, and from working with this group I had learned a lot about language design. This is the origin of many Python features, including the use of indentation for statement grouping and the inclusion of very-high-level data types (although the details are all different in Python).
I had a number of gripes about the ABC language, but also liked many of its features. It was impossible to extend the ABC language (or its implementation) to remedy my complaints -- in fact its lack of extensibility was one of its biggest problems. I had some experience with using Modula-2+ and talked with the designers of Modula-3 and read the Modula-3 report. Modula-3 is the origin of the syntax and semantics used for exceptions, and some other Python features.
I was working in the Amoeba distributed operating system group at CWI. We needed a better way to do system administration than by writing either C programs or Bourne shell scripts, since Amoeba had its own system call interface which wasn't easily accessible from the Bourne shell. My experience with error handling in Amoeba made me acutely aware of the importance of exceptions as a programming language feature.
It occurred to me that a scripting language with a syntax like ABC but with access to the Amoeba system calls would fill the need. I realized that it would be foolish to write an Amoeba-specific language, so I decided that I needed a language that was generally extensible.
During the 1989 Christmas holidays, I had a lot of time on my hand, so I decided to give it a try. During the next year, while still mostly working on it in my own time, Python was used in the Amoeba project with increasing success, and the feedback from colleagues made me add many early improvements.
In February 1991, after just over a year of development, I decided to post to USENET. The rest is in the
Misc/HISTORYfile.
Python is a high-level general-purpose programming language that can be applied to many different classes of problems.
The language comes with a large standard library that covers areas such as string processing (regular expressions, Unicode, calculating differences between files), Internet protocols (HTTP, FTP, SMTP, XML-RPC, POP, IMAP, CGI programming), software engineering (unit testing, logging, profiling, parsing Python code), and operating system interfaces (system calls, filesystems, TCP/IP sockets). Look at the table of contents for :ref:`library-index` to get an idea of what's available. A wide variety of third-party extensions are also available. Consult How does the Python version numbering scheme work?
Python versions are numbered A.B.C or A.B. A is the major version number -- it is only incremented for really major changes in the language. B is the minor version number, incremented for less earth-shattering changes. C is the micro-level -- it is incremented for each bugfix release. See those precede 2.0.
You may also find version numbers with a "+" suffix, e.g. "2.2+". These are unreleased versions, built directly from the CPython development repository. In practice, after a final minor release is made, the version is incremented to the next minor version, which becomes the "a0" version, e.g. "2.4a0".
See also the documentation for :data:`sys.version`, :data:`sys.hexversion`, and :data:`sys.version_info`.
The latest Python source distribution is always available from python.org, at https://github.com/python/cpython/.
The source distribution is a gzipped tar file containing the complete C source, Sphinx-formatted documentation, Python library modules, example programs, and several useful pieces of freely distributable software. The source will compile and run out of the box on most UNIX platforms.
Consult the How do I get documentation on Python?
The standard documentation for the current stable version of Python is available at https://docs.python.org/3/download.html.
The documentation is written in reStructuredText and processed by I've never programmed before. Is there a Python tutorial?
There are numerous tutorials and books available. The standard documentation includes :ref:`tutorial-index`.
Consult Is there a newsgroup or mailing list devoted to Python?
There is a newsgroup, :newsgroup:`comp.lang.python`, and a mailing list, :newsgroup:`comp.lang.python` is high-traffic, receiving hundreds of postings every day, and Usenet readers are often more able to cope with this volume.
Announcements of new software releases and events can be found in comp.lang.python.announce, a low-traffic moderated list that receives about five postings per day. It's available as https://www.python.org/community/lists/.
Alpha and beta releases are available from https://www.python.org/; an RSS feed of news is available.
You can also access the development version of Python through Git. See How do I submit bug reports and patches for Python?
To report a bug or submit a patch, please use the Roundup installation at password reset procedure.
For more information on how Python is developed, consult Are there any published articles about Python that I can reference?
It's probably best to cite your favorite book about Python.
The very first article about Python was written in 1991 and is now quite outdated.
Guido van Rossum and Jelke de Boer, "Interactively Testing Remote Servers Using the Python Programming Language", CWI Quarterly, Volume 4, Issue 4 (December 1991), Amsterdam, pp 283--303.
Yes, there are many, and more are being published. See the python.org wiki at
The Python project's infrastructure is located all over the world and is managed
by the Python Infrastructure Team. Details Why is it called Python?
When he began implementing Python, Guido van Rossum was also reading the
published scripts from , a BBC comedy series from the 1970s. Van Rossum
thought he needed a name that was short, unique, and slightly mysterious, so he
decided to call the language Python. No, but it helps. :) Very stable. New, stable releases have been coming out roughly every 6 to 18
months since 1991, and this seems likely to continue. Currently there are
usually around 18 months between major releases. The developers issue "bugfix" releases of older versions, so the stability of
existing releases gradually improves. Bugfix releases, indicated by a third
component of the version number (e.g. 3.5.3, 3.6.2), are managed for stability;
only fixes for known problems are included in a bugfix release, and it's
guaranteed that interfaces will remain the same throughout a series of bugfix
releases. The latest stable releases can always be found on the it will not
be maintained after January 1, 2020. There are probably tens of thousands of users, though it's difficult to obtain
an exact count. Python is available for free download, so there are no sales figures, and it's
available from many different sites and packaged with many Linux distributions,
so download statistics don't tell the whole story either. The comp.lang.python newsgroup is very active, but not all Python users post to
the group or even read it. See past Python conferences will reveal contributions from many
different companies and organizations. High-profile Python projects include the Zope application server. Several Linux distributions, most notably What new developments are expected for Python in the future?
See
New development is discussed on Is it reasonable to propose incompatible changes to Python?
In general, no. There are already millions of lines of Python code around the
world, so any change in the language that invalidates more than a very small
fraction of existing programs has to be frowned upon. Even if you can provide a
conversion program, there's still the problem of updating all documentation;
many books have been written about Python, and we don't want to invalidate them
all at a single stroke. Providing a gradual upgrade path is necessary if a feature has to be changed.
Is Python a good language for beginning programmers?
Yes. It is still common to start students with a procedural and statically typed
language such as Pascal, C, or a subset of C++ or Java. Students may be better
served by learning Python as their first language. Python has a very simple and
consistent syntax and a large standard library and, most importantly, using
Python in a beginning programming course lets students concentrate on important
programming skills such as problem decomposition and data type design. With
Python, students can be quickly introduced to basic concepts such as loops and
procedures. They can probably even work with user-defined objects in their very
first course. For a student who has never programmed before, using a statically typed language
seems unnatural. It presents additional complexity that the student must master
and slows the pace of the course. The students are trying to learn to think
like a computer, decompose problems, design consistent interfaces, and
encapsulate data. While learning to use a statically typed language is
important in the long term, it is not necessarily the best topic to address in
the students' first programming course. Many other aspects of Python make it a good first language. Like Java, Python
has a large standard library so that students can be assigned programming
projects very early in the course that do something. Assignments aren't
restricted to the standard four-function calculator and check balancing
programs. By using the standard library, students can gain the satisfaction of
working on realistic applications as they learn the fundamentals of programming.
Using the standard library also teaches students about code reuse. Third-party
modules such as PyGame are also helpful in extending the students' reach. Python's interactive interpreter enables students to test language features
while they're programming. They can keep a window with the interpreter running
while they enter their program's source in another window. If they can't
remember the methods for a list, they can do something like this: With the interpreter, documentation is never far from the student as they are
programming. There are also good IDEs for Python. IDLE is a cross-platform IDE for Python
that is written in Python using Tkinter. PythonWin is a Windows-specific IDE.
Emacs users will be happy to know that there is a very good Python mode for
Emacs. All of these programming environments provide syntax highlighting,
auto-indenting, and access to the interactive interpreter while coding. Consult
the edu-sig mailing list.
Where in the world is www.python.org located?
Do I have to like "Monty Python's Flying Circus"?
Python in the real world
How stable is Python?
How many people are using Python?
Have any significant projects been done in Python?
>>> L = []
>>> dir(L) # doctest: +NORMALIZE_WHITESPACE
['__add__', '__class__', '__contains__', '__delattr__', '__delitem__',
'__dir__', '__doc__', '__eq__', '__format__', '__ge__',
'__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__',
'__imul__', '__init__', '__iter__', '__le__', '__len__', '__lt__',
'__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__',
'__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__',
'__sizeof__', '__str__', '__subclasshook__', 'append', 'clear',
'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove',
'reverse', 'sort']
>>> [d for d in dir(L) if '__' not in d]
['append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']
>>> help(L.append)
Help on built-in function append:
<BLANKLINE>
append(...)
L.append(object) -> None -- append object to end
<BLANKLINE>
>>> L.append(1)
>>> L
[1]
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