Accessibility testing is the type of systems testing designed to find whether individuals with disablements will be able to use of the system, which could be software, hardware, and some other type of system. Impairments can be of any type like people can have a vision problem, hearing problem, inability to use key board or mouse, reading difficulties and so on.
So for those peoples our system should be able to accessible.
Invite customer site people to our company premises and give demo to them on s/w build. Developer and tester can take direct feedback from customer site people. It is always performed by the developers at the software development site. Alpha Testing is not open to the market and public. It comes under the category of both White Box Testing and Black Box Testing. It is always performed within the organization.