A python egg is a file used for distributing python projects as bundles; it is usually compressed with the zip algorithm. Egg files normally include some metadata; the file extension is ".egg". The concept is very similar to a Java .jar file.
An egg is a bundle that contains all the package data. In the ideal case, an egg is a zip-compressed file with all the necessary package files. But in some cases, Python's setuptools decides (or is told via CLI switches) that a package should not be zip-compressed. In those cases, an egg is simply an uncompressed subdirectory, but with the same contents. The single file version is useful for transporting, and saves a little bit of disk space, but an egg directory is functionally and organizationally identical. The concept is very similar to a Java .jar file.
You may use an egg simply by pointing your shell environment's PYTHONPATH or Python's sys.path at it and importing as you normally would, for Python versions >= 2.5. If you wish to take this approach, you do not need to bother with setuptools or ez_setup.py at all.
