Some Drupal sites don’t allow regular users to log in at all; they may only be used by administrators. In such cases it may be desirable to lock down access to the login and admin screens. This can be done using htaccess.
Web site content must be served in such a way that a visitor with visual or hearing impairments can consume substantially the same content, even if in alternate form. This involves images with alternative text, video and audio with closed captioning, and adjusting the page markup to cater to screen readers and other assistive technology.
When large organizations build or rebuilt their sites, they may face a dilemma if they have divisions requiring their own web presence. It may be tempting to use Drupal’s multisite option for this, but the pros and cons need to be carefully weighed.