ArcPy is a site package that builds on (and is a successor to) the successful arcgisscripting module. Its goal is to create the cornerstone for a useful and productive way to perform geographic data analysis, data conversion, data management, and map automation with Python.
This package provides a rich and native Python experience offering code completion (type a keyword and a dot to get a pop-up list of properties and methods supported by that keyword; select one to insert it) and reference documentation for each function, module, and class.
The additional power of using ArcPy within Python is the fact that Python is a general-purpose programming language. It is interpreted and dynamically typed and is suited for interactive work and quick prototyping of one-off programs known as scripts while being powerful enough to write large applications in. ArcGIS applications written with ArcPy benefit from the development of additional modules in numerous niches of Python by GIS professionals and programmers from many different disciplines.
Python provides the facility of documentation strings. The functions and classes available in ArcPy use this method for the package documentation. One method for reading these messages and getting help is by using the command help provided by Python. Running the command with an argument displays the calling signature and the documentation string of the object.
>>> import arcpy >>> help(arcpy)
Another method for getting help is the code completion provided by ArcPy. Anytime you type in a function name and begin to enter arguments, the help and function usage is displayed in the help window.