Before starting with the visual and technical design of your site you need to define the structure of your website. All the content and functionality needs to be structured in a suitable manner for your audience.
The website or application needs some kind of security level but you do not want the security to get in the way of your users.
The user needs to manage a large amount of information and to be able to find the various items at any time. The user may also want to share ideas and resources with others.
You have an website that addresses an international audience, that interacts with your website and/or your services.
You have an interesting article and want to give it a suitable title and advertise a link to the article somewhere else.
Users register on a website and create a login and password. It is likely that users will forget the password and/or login at some point. You should cater for password recovery so that they can log in again.
You want to offer an article online to your users. It is fatiguing to read on a screen due to the fact that screens give off light and do not have the same resolution as printed media.
Users want to find an item in a large amount of content. Users often do not know exactly what their choice of items will be at the end of a search, e.g. if you are looking for a small, cheap camera, the choice will often depend on the offerings on the website.