The snare drum is not only the most important drum of the drum kit, but it's the most important instrument in a song as well (besides the vocal) since it provides both the backbeat and the energy. That's why it's important for every engineer and producer to know as much about making the snare sound great as possible.
You can have a killer sounding snare and a wimpy sounding kit and that snare will make everyone believe that the entire kit sounds killer, while a wimpy sounding snare will make even a great sounding kit sound a lot worse than it is.
Here's a great video about tuning the snare. It doesn't get into the different heads like in the last snare video I posted, but it's really the nitty gritty of tuning the drum up, which is essential to that killer sound that everyone wants and needs.