Bicycle pedals at cheap prices from starbike.com, your online bike shop
The pedals on a bicycle are, besides the handlebar and the saddle the central link between the rider and the bike. The power from the legs is transfered by the pedals Pedale to the crank arms.
The pedals are threaded into the cranks and spin freely around their own axle. The axle is surrounded by bearings. Most modern pedals come with durable cup and cone bearings or industrial-grade cartridge bearings.
Platform pedals need to provide enough grip for regular shoes. To prevent slipping, the contact area profile is shaped, but for road riders and many mountainbikers in wet and muddy conditions this isn't enough.
That's where pedal with a binding come in. Manufacturers like LOOK, Crank Brothers or Shimano offer a huge range of pedals, where you click into with special cleats mounted to cycling shoes. During riding it's not possible to accidentially slip-out of them. Releasing your feet requires a side-step movement. Another positive effect is the possibility to pull-up (platform pedals can only be pushed), which results in a "round" pedaling scheme for more efficiency and better muscle use. The power to release can be adjusted on almost all models, because beginners often prefer a low-effort in order to get used to the release process.
There are also hybrid models which feature both a contact area for regular shoes and a cleat binding mechanism.