Blogs what are they and who is using them

I hear Blog this and blog that and she is a blogger…. what does all this mean? Who is using blogs and why? I have found it somewhat hard to connect or simply find certain blogs of topic… what is the fuss all about? Do large search engines pull up these blogs? It’s states that the blog is ” public” any experience or advice on the best way to utilize this app WordPress would be helpful. Thank you.