John Udell of O'Reilly Digital Media describes a screencast as "a digital movie in which the setting is partly or wholly a computer screen, and in which audio narration describes the on-screen action."
Screencasting is an excellent way of creating short tutorials or providing and demonstrating examples of a particular online feature.
Accessible practices to consider:
Watch a sample screencast tutorial made in Camtasia Studio, from TechSmith.
See more Camtasia-made tutorials for Camtasia Studio version 8, from TechSmith.
Read the official Camtasia Studio User Guides
Download a free trial of Camtasia Studio for Mac or Windows.