SED is short for "Stream EDitor".

Unlike emacs or vi it is not an interactive editor
but more like a "filter" which allows for use in scripts.

A typical use from the command line looks like this:
sed -e "command" inputfile > outputfile

SED makes use of "regular expressions"
to detect patterns within the text.
So some knowledge about "regex" is highly recommended.

Please read the sed one-liners for examples.
The cover many questions asked on the list.
(see Links)

[2005-07-19]