Gliders are featured in Mario Kart 7 , Mario Kart 8 and Mario Kart 8 Deluxe. When players drive off of a blue ramp or Boost Pad on the edge of a cliff (or something of the related sort), the Glider will appear and will make the player slowly descend in the air for a short time.
Players can control which way the kart moves when gliding; left, right, dive (down), or even slowing down the descend a bit (which is up).
Whenever there is a gliding area, there is normally obstacles in the air to slow the player down. Sometimes (if the player hits an obstacle) the player will actually fall out of the air and land on the track below him or her, normally slowing the player down by a little.
If done correctly, gliding can be very helpful and can even speed the player up.
Mario Kart 7
Mario Kart 8