What exactly is Implantation bleeding ?


So I’ve been experiencing some bleeding on and off all day yesterday but AF isnt due until 12/17. I’ve been trying to read up on implantation bleeding but it’s very general and sounds kinda like period spotting, so for those of you who got pregnant and experienced implantation bleeding what was it like. Heavy, light, brownish, bright red? Etc. and how long did it last?