There are 5 ranges of combat, but many martial artists only train in one or two of those ranges.  Ideally though you should be at least familiar with each of those ranges to be a complete martial artist and not have any gaping blind spots!  

I know that many of my listeners will already be familiar with https://www.grapplearts.com but also check out my self defense oriented website https://www.selfdefensetutorials.com