Two Basic Types of Augmentative and Alternative Communication Devices: Aided and Unaided.

There are two main types of AAC—aided and unaided systems. 
Aided systems 
An aided system rely on a tool outside of the body such as an alphabet board, static board, picture exchange system, writing or a speech generating device (e.g. dedicated communication system, tablet, smart phone) to communicate. There are two types of aided systems—basic and high-tech. A pen and paper is a basic aided system. Pointing to letters, words, or pictures on a board is a basic aided system. Touching letters or pictures on a computer screen that speaks for you is a high-tech aided system. It is not uncommon that one uses a combination of both forms of communication in a single day.  
Unaided Systems  
Unaided systems do not need anything but your own body to use them. These include gestures, body language, facial expressions, and some sign vocabulary.

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