Messages that are composed and stored ahead of time so they can be delivered in a timely manner. Some are urgent messages (e.g. I need help!) and others are social messages (e.g. "You are exactly right!"). They are the opposite of novel utterances created by the user at the time of communication. An individual cannot obtain true independence in AAC with only access to preprogrammed utterances.

In aids with a large vocabulary, there has to be a way to select vocabulary that is not immediately visible to the user. There are three common strategies: levels, dynamic displays, and encoding.

The way in which the user interacts with a device to control it for communication, e.g. pointing, single-switch scanning, etc. (Beukelman & Mirenda, 1998)

A technique or strategy used to speed up AAC output because it is so much slower than speech. Most rate enhancements can be grouped into two types: encoding and prediction.

Abbreviation for Speech-Language Pathologist, a professional who provides assessment and treatment for people with communication, feeding, and/or swallowing challenges.

A complex system of signing English that uses the grammatical features of prefixes, suffixes and tenses (Beukelman & Mirenda, 1992)

refers to how well an individual understands communication, whether it is speech, sign or writing. It contrasts with expressive communication.

An "indirect selection" technique in which items are presented sequentially one at a time and the individual activates a switch or otherwise signals to accept one of the items when presented. Scanning, like other indirect selection techniques, is only intended for individuals who do not have sufficient motor control for direct selection techniques.

means that the individual is able to communicate what he/she intends to communicate, not accidentally push another key or convey a message that was not intended. Reliability is crucial to independence.

The items (vocabulary/symbols) available to a specific AAC user for communication. They may be presented in a visual, auditory, or tactile form, depending on the user's needs. (Beukelman & Mirenda, 1998)