There may come a day where you wish a graphic you had was SVG, but you only have it in raster, like GIF, JPG, or PNG.
In this video we look at an example of that. We have this arrow graphic that is GIF, but really should be SVG when used on the web. Illustrator is pretty good at turning raster into vector with it's Live Trace tool (apparently now called Image Trace). There are lots of settings and stuff to learn about it, but for something super basic like this, it'll probably do it perfectly without much help.
Then we clean it up and get it to be a nice simple shape without any extra cruft.
Adobe Shape is a pretty neat iOS app that snags vector right from pointing your camera on the phone at stuff.
Another tool specifically for raster-to-vector is Vector Magic.