Essentially ‘Grappling’ is a generic term for any Jiu Jitsu/Wrestling based sport. Another name would be No Gi Submission Wrestling. Your aim is to learn to use the bodies natural levers, frames and fulcrums to create leverage, to navigate a way through your opponents defences and ultimately force them to Submit (This is also known as Tapping Out). This could be a choke, an arm lock, a foot or shoulder lock or one of many other possibilities.
Kate Jackson submitting Eeva Siiskonen with a guillotine choke
Like any good science this art is very measurable and does not contain any sort of ‘Chi’, ‘Inner Energy’ or other ‘mumbo jumbo’. Everything you are shown works, and will work on compliant as well as non compliant training partners.