Sometimes you need to know why a part of your files is the way it
is, who made that particular change and why. Or in other words:
"Who the h*** put that command there?".
Subversion has a command for this, and it is called blame
(guess why). Subversion creates a blame of a file by adding information
about the author who committed a line, the revision the line was last
changed and the date.
TortoiseSVN has its own tool to show you those blames. In addition to
the information other Subversion clients show, it also shows you
the log message of the commit for each line inside a little tooltip
window when you hover the mousepointer over a line.
To make it easier to follow a specific revision (which lines exactly
were changed in a commit), it colors lines from the same revision
differently. Also a separate color is used for the author of the
currently selected line.