sed script

I am beginner for Unix. I practicing unix shell script. I worked out some sed script example from internet. Everything fine.

But in real unix environment, where sed script is mainly used.?
Can anyone give some examples for the usage of sed script in real unix environment. It will be useful for my preparation.

Thx,. reg, green

It may be needed when you are asked to get something out of a text file, like to analyze an access log file.
In general, you might need it when you process text files, cause SED, AWK, and many other tools available on *nix systems are text based, they are very useful, and convenient.