A blog is a type of website, usually created by an individual, that is updated regularly with commentary, event updates, photos, or other types of media. The word blog is a shortened version of the word "weblog". The video below gives a good description of the purpose of blogs, and how they are being used in the 21st century:
Students can have others besides the teacher read their work.
Students can get "live" feed back from others.
Blogs provide reading and writing practice in yet another form.
Shy students are encouraged to participate in a way they see as non-threatening.
Overall participation is encouraged and creates a sense of teamwork and community.
Increase student-student, teacher-student, and family-classroom communication.
Online student learner journal
Communication of classroom activities to families and outsiders
Student portfolios
Space created for pre- or post-class discussion
Method of submitting assignments so that students can view others' work
Once you choose your blog site, the resources you use will usually be specific to that site format. On the individual blogging sites, there are often video tutorials, user forums, and support forms where you can go to find the answer to whatever stumps you!