An important part of becoming “good” at a language is becoming familiar with its library eco-system.

The official Python Standard Library reference manual rocks.

Module Category Description
argparse functions for parsing command line arguments
atexit allows you to register functions for your program to call when it exits
bisect bisection algorithms for sorting lists (see Chapter 10)
calendar a number of date-related functions
codecs functions for encoding and decoding data
collections a variety of useful data structures
concurrent asynchronous computation
copy functions for copying data
csv functions for reading and writing CSV files
datetime classes for handling dates and times
fileinput file access iterate over lines from multiple files or input streams
fnmatch functions for matching Unix-style filename patterns
glob functions for matching Unix-style path patterns
io functions for handling I/O streams and StringIO, which allows you to treat strings as files.
json functions for reading and writing data in JSON format
logging access to Python’s own built-in logging functionality
multiprocessing allows you to run multiple subprocesses, while providing an API that makes them look like threads
operator functions implementing the basic Python operators, instead of writing your own lambda expressions
os swiss army knife access to basic OS functions
pprint data types data pretty printer
random functions for generating pseudorandom numbers
re regular expression functionality
sched an event scheduler without using multithreading
select access to the select() and poll() functions for creating event loops
shutil file access access to high-level file functions
signal functions for handling POSIX signals
tempfile file access functions for creating temporary files and directories
threading access to high-level threading functionality
urllib provides functions for handling and parsing URLs
uuid allows you to generate Universally Unique Identifiers (UUIDs)