what is a blog ?

Dear Sydmack, 

Blog is a term that described an online-journal (personal diary). It
derives from the term "web log".

You can read further definitions here: 
Google Define:blog
<://www.google.com/search?hl=en&q=define%3Ablog&btnG=Google+Search> 

And here: 
Answers.com: Blog
<http://www.answers.com/blog&r=67> 

You can open your own blog (and see examples of people's blogs) on
several websites:

Blogger
http://www.blogger.com/ 

Examples of blogs: 

Blog for America
http://www.blogforamerica.com/ 

Lawrence Lessig Blog
www.lessig.org/blog/ 

Boing Boing: A Directory of Wonderful Things
http://www.boingboing.net/ 

Google Blog
Official blog.
http://googleblog.blogspot.com/ 

Blog Maverick - www.blogmaverick.com _
Maintained by Mark Cuban, owner of the Dallas Mavericks.
www.blogmaverick.com/ 

You can see a directory of blogs here: 
Blogwise - Blog directory
http://www.blogwise.com/

I hope this answers your question. Please contact me if you need any
further clarification on this answer before you rate it.