Compression
The coding of data to save storage space or transmission time. Although data is already coded in digital form for computer processing, it can often be coded more efficiently (using fewer bits). There are many compression algorithms and utilities. Compressed data must be decompressed before it can be used.
Source: Free Online Dictionary of Computing - http://foldoc.doc.ic.ac.uk/foldoc/foldoc.cgi?query=compression

Compression with WinZip
When you compress a file with WinZip, you actually do two things: first, you create an "archive", which is a container for your compressed file and second, you compress the file. The final product will be a file with the extension ".zip". You can also use WinZip to create a self-extracting file, which will not require Wizip to uncompress when you get back to your home/office.

• Creating A New Archive
  1. Select New Archive from the File menu and name the archive for your zipped files.
     
  2. Select Actions > Add or click the Add button
  3. Select the files to add to the archive.
  4. After the files are selected, click to add the files.
     
• Make New Archive Self-Extracting
  1. Choose "Make EXE" from Actions menu
• Save "whatever.exe".