From the authors:
The ARASAAC portal offers graphic resources and materials to facilitate communication for those with some sort of problem in this area.
This is an increasingly popular and widely used AAC resource, and the symbol file libraries are available with the file names translated into a growing number of languages. The file format provided is 500 pixels high PNG. Though the number of files is quite large, there is a fair amount of redundancy due to numerous duplication of symbols labelled with different names.