Notes:
low vision
= people wearing glasses
= color blindness (3 types: proteranope, deuteranope, triteranope)
mobility impaired
= can't use a mouse (can be me or you is mouse is broken or unplugged)
= have to use an adapted keyboard (bigger, or with lesser keys, braille terminal)
all other: with different browsers, different screen size, different screen resolution, different plugin...