Kayaking is the use of a kayak for moving across water. Kayaking is generally differentiated from canoeing by the fact that a kayak has a closed cockpit and a canoe has an open cockpit. However, there are many sit-on-top kayaks, and these boats are growing in popularity. They also use a two bladed paddle. Another major difference is in the way the paddler sits in the boat. Kayakers sit in a seat on the bottom of the boat with their legs extended out in front of them. Canoeists will either sit on an elevated bench seat or kneel directly on the bottom of the boat.

Whitewater kayaking involves taking a kayak down rapids. Sea kayaking sometimes also referred to as Ocean Kayaking involves taking kayaks out on to the ocean or other open water e.g., a lake. Sea kayaking can involve short paddles with a return to the starting point or "put-in" or expeditions covering many miles and days. Kayaking of all kinds has continued to increase in general popularity through the 1990s and early 21st century.

Kayaks are classified by their intended use. There are six primary classifications: slalom, whitewater, surf, touring/expedition, light touring/day tripping and general recreation. From these primary classifications stem many sub-classes. For example, a fishing kayak is simply a general recreation kayak outfitted with features and accessories that make it an easier kayak from which to fish. Also within these classifications are many levels of performance which further separate the individual models. In other words, not all touring kayaks handle the same.

There are two major configurations of kayaks - "sit on tops" which as the name suggests involves sitting on top of the kayak in an open area and "cockpit style" which involves sitting with the legs and hips inside the kayak hull and a "spray skirt" that creates a watertight barrier around the waist. Whether a kayak is a sit-on-top or a cockpit style has nothing to do with which classification it falls under. Both configurations are represented in each of the five primary classifications. While most kayaks are designed to be paddled by a single person, other configurations include tandem and even triple cockpit boats.

Because of their range and adaptability, Kayaking is popular amongst divers, fishers, and adventure enthusiasts.