"drop beats"? in Hip hop

[Pbassred]

Hip hop:- What is a "drop beat"?
I've been asked to play bass for a band. The tracks don't seem any trouble at all but the phase puzzles me.

[JimK]

Not playing on 'the 1'.

Sample rhythm on "1"-
l1---2---3&a4---l

Dropping "1"-
l--&-2---3&a4---l
Basically, displaced "1" to the "& of 1"

Dropping/displacing more beats-
l--&---&--&a4e--l
More of a Backbeat bass figure.