This is list of software you can use for the sorts of files you encounter when getting ebooks. All of these are freely downloadable.

1. Unarchivers

These are software tools useful for extracting ebooks from so-called archive files (files with names ending in *.zip, *.rar, *.7z, to name a few).

• 7-Zip (7-Zip Portable)
• PeaZip (PeaZip Portable)

2. Readers

These are software for reading ebooks. The following formats are usually encountered:

a. PDF

• Adobe Reader
• Foxit Reader (Foxit Portable)
• Sumatra PDF (Sumatra Portable)

b. DjVu

• DjVu Browser Plug-in
• WinDjView

c. CHM
Apart from the built-in reader in most Windows machines, here are some alternatives (that also work for Linux):

• FBReader
• CHM Reader (Firefox extension)

d. EPUB

• FBReader
• EPUBReader (Firefox extension)