A blogroll is typically found in the sidebar of a blog and it includes links to other blogs that the blogger recommends. A blogroll can be divided into categories if there are a number of blogs included that all discuss different topics. The way that a blogroll is set up varies as each blogger has their own personal preference.
If a blogger includes a link to a blog in their blogroll, it could mean that they are expecting a link back from that blog. However, a blogger is not required to reciprocate and a blogger is not required to have a blogroll at all.
If you get your blog listed on another blogger’s blogroll, it can be great for generating traffic and gaining exposure from a new audience. Including a blogroll on your blog can improve relationships among other bloggers, but also may result in visitors leaving your blog to check out the other blogs that you recommend.