In addition, aids and services include a wide variety of technologies including 1) assistive listening systems and devices; 2) open captioning, closed captioning, real-time captioning, and closed caption decoders and devices; 3) telephone handset amplifiers, hearing-aid compatible telephones, text telephones (TTYs) , videophones, captioned telephones, and other voice, text, and video-based telecommunications products; 4) videotext displays; 5) screen reader software, magnification software, and optical readers; 6) video description and secondary auditory programming (SAP) devices that pick up video-described audio feeds for television programs; 7) accessibility features in electronic documents and other electronic and information technology that is accessible (either independently or through assistive technology such as screen readers) .
The guidelines are broken down by four main principles: perceivable, operable, understandable, and robust. Under each principle, there are guidelines that provide specific goals a website should work toward. Under each guideline, there are testable success criteria. Those criteria are graded A, AA, or AAA. This grade shows the level of conformity to accessibility, AAA being the highest. The law only requires A and AA guidelines to be met.