You can think of a blog as a website that's easy to update. You might use one to broadcast work you're doing on a research project, or as the main face of a student group.
Simmons students looking for a personal blog should use Google Blogger, which is part of your Google Apps account.
If you have a student organization or ongoing project, or you are SLIS faculty, you can request a WordPress blog, made available by the SLIS Technology Group: Request a Blog
Student Group Blogs
Simmons SLIS Blogs