>>1952432>>"UGHH IT'S ACHKSHUALLY CALLED CLIPLESS BECAUSE..."In the old days pedal foot retention consisted of toe-cages and straps. The toe-cages were called clips. You would have cleats under your shoes that hooked up with the pedal and you would tighten down with the strap so your feet were firmly fastened to your pedals. This was cumbersome, inconvenient and frankly quite dangerous, so someone invented a different trap mechanism that would make it easier to clip in and out. These pedals didn't have clips, so they were called clipless. But you still clip into them, leading to continuos confusion among newbies and obstinate people like anon above.
Clips are still used today by some, particularly by fixie hipsters, albeit practically never with the cleats. And they are not commonly referred to as clips anymore, further adding to the confusion.
tl;dr you clip into your clipless pedals because of historical reasons.
Pedals without foot retention are usually referred to as platform pedals of flat pedals.