A kayak is a small, narrow, human-powered watercraft, typically propelled by a double-bladed paddle, where the paddler sits facing forward, with legs in front. 

Here's a more detailed description:

Design:

Kayaks are characterized by their low-to-the-water profile and enclosed decks, with a cockpit where the paddler sits. 

Propulsion:

Kayaks are propelled by a double-bladed paddle, where the paddler pulls the paddle front-to-back on one side and then the other in rotation. 

History:

The traditional kayak, used by Inuit and other indigenous peoples, was a fast, seagoing craft for hunting seals and walruses. 

Modern Kayaks:

Modern kayaks come in various designs and materials, including sit-on-top and inflatable models, catering to different purposes and skill levels.