A wiki page is designed to be intuitive and easy to get up and running with SharePoint pages. A wiki page is similar to an Office Word document. You place the page in Edit mode and start adding content.
Just like a Word document, you have the Ribbon at the top to format text and insert items. And when you want to get advanced and modify the HTML, all you need to do is click a button to edit the source code.
Only members of your team site’s default Members group have permission to modify wiki pages. If you want some people to be able to read your wiki pages but not edit them, add those users to your site’s default Visitors group.
A Wiki Content page consists of a very editable region where you place your content. In this editable region, you can place almost any kind of content imaginable — freeform text, tables, hyperlinks, images, even Web Parts. A Wiki Content page combines the best aspects of a typical wiki page with a Web Part page.
You can create new Wiki Content pages for your site by clicking the Settings gear icon and choosing Add a Page. (The Settings gear icon is found in the upper-right corner of the page.) These new Wiki Content pages are also stored in the Site Pages library.
You can create additional wiki page libraries if you want to manage a specific wiki topic in your site.