# Are there good comprehensive lists of LaTeX commands online?

I'm relatively new to actual LaTeX scripting, much of my experience comes from using MathJax over at math.stackexchange.com and I'm kinda self-taught, just picking things up as I need them. However, I'd like to write an entire paper in LaTeX now and I need to do a bit more than MathJax offers to me, such as page allignment, font selection, etc. However, it would be nice to view a list of all (or most) the commands, preferably categorized and easy to navigate. Does such a place exist and where can I find them?