Are SLR Camera Lens compatible with a Digital Camera?

I'm thinking about purchasing a new Digital DSLR camera, but am wondering if the lens I currently have for my Nikon N90 SLR are compatible. Any advice?

All lenses that work on your N90 will mount on any Nikon DSLR.

But be aware that only AF-S and AF-I lenses will autofocus on entry level DSLRs such as the D3100 or D5100. If your lenses "only" are AF ones instead of the above, then you'd need a D90 or D7000 or upwards for them to autofocus, as only those DSLRs have a autofocus motor in the body.