What is short shutter lag?

Nikon D7000 has a 50ms Shutter Lag. Is that good, or are there better options?

Shutter lag is the time between pushing the button and actually capturing/taking the photograph.

50ms is 50/1000 of a second or 1/20 of a second. That's not bad at all. I'm sure there are better options but I can't control my finger for a range of 1/20 of a second so I'm pretty sure it is insignificant.

I would agree about lag time. More specifically it's the time between your half press and when the camera has gathered proper exposure and focus information to make a photo.

The shorter time the better. Most dslr cameras are very quick but it also depends on the lens.
I have one, bad experience with Tamron, lens that takes for ever to find focus and it's still out.
Another lens by Canon simply snaps to focus and exposure.

50ms is 50/1000 of a second. That's a pretty short time and faster than you can blink!

What that means is that the D7000, like most modern DSLR's, virtually snaps the picture immediately after you press the shutter button.

Compact digital cameras are notorious for shutterlag, that often means the camera snapping the picture after the subject (or photographer) has moved.

That's why you find sports photographers and photojournalists using DSLR's and not compact digitals.

A lag of 50 ms is pretty good, suitable for most types of shooting except very fast action shooting. Remember that autofocus can also influence lag, depending on the kind of lens you have mounted.Pro lenses with piezoelectric actuators (AF-S, ultrasonic, etc.) can focus much faster than lenses that are driven by the camera body or lenses with conventional motors.

For very low lag, shoot film with a rangefinder… The lag is practically zero for such cameras. Of course, they have drawbacks as well.