....I dont completely understand the concept . Does the bass and kick always have to be syncronized ?? What if the bass is playing a walking line or something melodic , in which case it'll be really weird having the kick play every note like a hi-hat .

I've also realized from around the forums , that the concept is to have the Tonal notes on the kick drum , and then in accents and rolls and fills , anything can be done or something like that . Can someone expand on that ??

....I dont completely understand the concept . Does the bass and kick always have to be syncronized ?? What if the bass is playing a walking line or something melodic , in which case it'll be really weird having the kick play every note like a hi-hat .

I've also realized from around the forums , that the concept is to have the Tonal notes on the kick drum , and then in accents and rolls and fills , anything can be done or something like that . Can someone expand on that ??

Locking in with the drummer means exactly what it says. it's all about timing and synchronization. Personally, I think that this concept should come natural to a gifted musician. Otherwise, if your rhythm and timing is not so hot, then perhaps a metronome would help.:)

It means "locking in with the drummer's timing", not "locking in with the kick drum only". The bassist's and the drummers timing should be the same, i.e. synchronized. This is Rule #1 to create a groove.

Imagine playing a busy funk line on the bass. Then think of a bass drum playing exactly the same rhythmic pattern over it. Does it sound good? Perhaps, but drummer is is likely playing way too much. It will probably sound much better if he recognizes the strong beats and play on only them instead. If fact, a simple beat (snare on 2 and 4, and bass drum on 1 and 3 or all four beats) played with the right attitude is often all you need.

It also has to do with the way you feel and express time.
Think of a beat. You can play directly on the beat.
Or you can play slightly ahead of the beat - a lot of trad jazz does this, (as did punk) and it gives a driving sound.
Or you can play slightly behind the beat - think Motown and R&B.

If you're playing ahead of the beat (pushing time) and the drummer is behind the beat (trying to groove) then the rhythm section sounds crappy.

If you and the drummer are feeling and expressing time the same way, then it "locks in".

Once in a while you meet a drummer who naturally expresses time the exact way you do. When you meet him you KNOW it. Everything locks, and people start asking what you guys charge as a rhythm section. :D