>

Greater than, when used in a mathematical context.
Example: x > y; this is read as x is greater than y

Right angle bracket in other contexts, in html and other markup languages it is used to end a directive.

In Bash (and i'd imagine other shells as well..), > is used to redirect the output of a program to a file. For example typing command > filename causes command to run, but any output from command is written into filename instead of printed into the screen. Note doing this will overwrite any information already in filename; using >> in place of a single > results in the output being appended to the end of the file instead.