User testing can be perfomed either remotely (ex. video conference) or in person with a user.
Usability testing is a method in which the user is given one or multiple
tasks to perform on the testing site, and an observer will note the
user's performance. Testing a website on multiple different browsers is
known as cross-browser testing. This is to ensure that necessary data
is displayed properly on all browsers, and for all users,
especially those with assistive programs or outdated browsers.