ADA Signs

The term "ADA Signs" has come into common use in the architectural, construction and signage industries with the advent of the Americans With Disabilities Act, or ADA. The Americans with Disabilities Act regulates accessibility; and includes requirements for signage that is conveniently located and easy to read both visually and through tactile touch. 
In common parlance, "ADA Signs" are often synonymous with braille signs. Signs with braille and raised characters are the most visible manifestation of the law requiring access to the built environment, but the sign standards in the ADA Accessibility Guidelines (or ADAAG) require much more than just braille and raised characters on some signs. 
In fact, the ADA dictates 3 broad categories of requirements.
1) Whether or a not a sign is required
2) Sign design requirements, including font, spacing and similar details
3) Precisely where a sign must be installed, and broad requirements dictating where signs may not be installed
In general, almost every sign that would be considered an "architectural" sign must comply with one or more of the ADA Guidelines. If a sign identifies a permanent room or space of a facility (including exits), directs or informs about functional spaces of the facility, or identifies, directs to, or informs about accessible features of the facility, it must comply. Signs for advertising and marketing purposes, temporary signs, company logos and names are examples of signs or sections of signs that do not have to comply.
Benefits.
Because of the rules requiring Braille on some signs, the signage section is most often considered as benefiting persons who are blind and visually impaired. Some of the sign guidelines are also designed to benefit persons with mobility or hearing impairments. Thorough wayfinding and room sign systems are also of benefit to deaf people, people who have problems speaking, and people with cognitive disabilities or psychiatric conditions that cause them to avoid speaking to strangers.
In addition, it is generally considered that easy to read and well thought out signage systems are of benefit to all stakeholders using a facility. 
Rules.
There are a number of general rules for signage:
Standards.
The standards for the signs (and most other standards used in ADA regulations and state building codes) are the product of the ANSI (American National Standards Institute) A117.1 Committee. This large committee is made up of a balanced group of representatives from industry, the government, disability organizations, designers, code officials, and experts. The committee meets in five year cycles to revise the last published standard. The standard is then used by the International Code Council for its model building code, and has formed the basis of the new version of the ADA Guidelines, now called the 2004 ADA/ABA. (However, with the final publication of the standards by the Department of Justice, we now generally refer to the Guidelines as the 2010 ADA Standards for Accessible Design.)
The standards had been already adopted by several federal agencies, and had been approved by the Department of Justice and were awaiting final review by the OMB when the Obama Administration came in. Although they are actually a product of the Clinton Administration and had taken eight years to make it through the Bush Administration, the Obama Administration considered them Bush Administration regulations, and held them up for review. They were approved by the Department of Justice for publication on September 15, 2010, and made legally enforceable on March 15, 2012.