Basically, it’s a developer-friendly grep that, by default, ignores many annoying things that tend to get in the way nowadays, such as .svn folders. Other common options, such as recursiveness and “operate on all files in this directory” are assumed without the need of explicitly typing them. The output is structured, colored and highlighted in a meaningful and useful way — but it still plays well in a pipe, where it reverts to a more sober, grep-like output. It maintains a small (but extendable) database of filetypes, so that you can ask for specific categories of files to be included or not: for instance –noshell ignores .sh, .bash, .csh, .tcsh, .ksh, and .zsh files.

It’s also actively maintained.

It’s already an indispensable tool for me. Go grab it, you won’t regret it!