Still being relatively new to all this, I wanted to clarify the different sort of "types" of actors that exist. I hear this term thrown around a lot, and I am aware what it means in a general sense, the type of roles you get based on your look. But is there a guideline anywhere of all the various types out there? Lets say someone like myself, a 25-year-old guy, who can play somewhere in his early 20s. What are the various "types" that could exist for someone in that age group? Also, would you say that most people get hired based off this type of look they tend to portray, or is there some overall wiggle room?

There's NO set guideline.

It's dependent upon YOU.

If you're of an obvious ethnic group, play that up as much as you can.

Get in a class where you'll be exposed to different roles. There you'll figure out the type of characters you can best play and enjoy.