BASE Jumping is similar to skydiving, however much more dangerous and risky.

BASE stands for Buildings, Antenna, Spans (Bridges) & Earth (Cliff). It is basically jumping with a parachute but from much lower altitude. Unlike Skydiving, here you are jumping from fixed platforms.
In Skydiving, you are jumping from an aircraft but the altitudes range from 9000 feet to 19000 feet. Skydiving involves free fall and gliding after the parachute is opened by you. You open your parachute at 4000 feet and then slowly glide down to ground zero. E.g. if you are jumping from 12000 feet, the first 8000 feet is the free fall wherein you are coming down at the speed of 130-150 kilometers per hour.

Once you reach the 4000 feet mark, which is a safe zone to open the parachute and then slowly fly around and land. Every second becomes important after 4000 feet and if your parachute is not opened till you reach 3000 feet mark, it is considered to be very dangerous and may prove to be fatal for the jumper.

However in case of BASE jumping, you are jumping from 3000 feet or sometimes much lower. Your margin of error is almost close to zero. You have to open your parachute within a couple of seconds of your jump. Any mistake means death. Here the possibility of fatality is 43 times higher than Skydiving.

Wingsuit BASE jumping is an innovation in terms of Suit that you wear while jumping. This suit helps to glide in the air with a little stability before you open the parachute. Wingsuit adds surface area to the human body to enable a significant increase in lift.