Grappling is way too polarizing, mostly because a character who is optimized to grapple won't fail grapples. It completely shuts down everything that isn't prepared with little effort. It heavily punishes heavy armor. The rules are also just not great, one of the biggest flaws in 3.5 was the grappling rules.
Pathfinder cleaned up the grappling a lot.
Here is the flowchart for pathfinder grappling.
http://pfsprep.com/e107_files/public/1482694608_186_FT297_grappleflowchart_1.0.pdfCMB is:
Combat Maneuver Bonus
Each character and creature has a Combat Maneuver Bonus (or CMB) that represents its skill at performing combat maneuvers. A creature’s CMB is determined using the following formula:
CMB = Base attack bonus + Strength modifier + special size modifier
CMD is:
Each character and creature has a Combat Maneuver Defense (or CMD) that represents its ability to resist combat maneuvers. A creature’s CMD is determined using the following formula:
CMD = 10 + Base attack bonus + Strength modifier + Dexterity modifier + special size modifier + miscellaneous modifiers