Wiki as a website
A wiki is a website. You can add text, images, videos, and even widgets to each page, and pages link to each other. The best part about a wiki is that it's not hard to edit. On some wikis, anybody can edit any page. On other wikis, authorized admins can edit the pages, while viewers can see the changes made to the pages immediately as they are updated in real time.
Wiki as a collaboration tool
In general, users can edit any page on a wiki. This makes a wiki the perfect place to collaborate and share information. The only way to share information properly is if everyone can report back at the same place, add their information, and everyone else can see the updated information. Blogs and other websites don't let just anyone edit the pages. Furthermore, they might require use of HTML, CSS, and JavaScript, making it difficult for the average person to update the website. This results in a loss of collaboration due to a high learning curve causing frustration and friction.
However, wikis eliminate this problem entirely. MyWikis offers a visual editor that allows anyone, even people completely new to wikis, to edit the pages using an easy-to-use interface offering similar features to Microsoft Word and Google Docs. Sharing documents on a shared drive and editing them is difficult to keep track of, difficult to organize, difficult to categorize, and most importantly, difficult to search for the right information. When you put your information on a wiki, you're making all of the information easily searchable using the wiki's powerful search engine.