Pls Help!

[botchers]

:confused:
To all experts:
Will you please help me to all of my questions regarding hashing algorythm? Hope you can help me. Coz I'm a bit confused..

1. What is a hashing algorythm? Please explain.
2. What it(hashing algorythm) can do?
3. Is there a ready-made hash algorythm that I can use to my application? If so, *refer to the next question
4. How can I use it to my application? example : delphi application

Thanks Sir's! :confused: