What is the difference between ABS and regular brakes?

I have a 1998 Silverado Ext. 5.7 liter

I bought it used and I dont know what the difference between ABS brakes and regular brakes are. I dont even know if I have ABS.

Did the 98 come with ABS or do you have to add that yourself?

Anyways it would be great to just know what the differences are, is ABS important?

ABS brakes is a system where when you apply the brakes it prevents the wheels from locking up. Going on ice or snow, or even wet roads, it will intermittedly pump the brakes as you hold the brake pedal down........ preventing you from locking the wheels up.
I don't know if you have them on your truck or if it's feasable to install them...... if you don't have them. I'm sure someone out there knows though.

I have a 98 Z71 with ABS on mine and more than likely you have it too... you'll notice it next time you hit the brakes really hard

It probably has antilock, check under the hood in the fuse/relay center for a 60 amp maxi fuse in the ABS slot and the ABS unit is usually close to the PCM with quite a few brake lines going to it, probably made by kelsey-hayes