|Built-in focus motor |
Some Nikon DSLRs don't have a lens focus motor built in, so they can only auto-focus with lenses that have a focus motor. Look for lenses labeled AF-S to make sure they'll auto-focus with Nikon DLSRs lacking a focus motor. In general the absence of a focus motor is only a concern for Nikon cameras.
Learn more about built-in focus motor.