why do we blog?

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Why do we blog? is it some way to get something off your chest or to just to talk with random people and debate? I don't know.......but it's funny that you can just blog about something random and people go ahead and comment or just have a plain conversation. I started this blog as an assignment I got from my teacher and i couldn't figure out what to blog about because I didn't want to sound like an idiot just randomly putting things out there for you to read. When I think about it though it's neat that you can talk about something good that happend to you or something to do with your job you or just a random thing and all you do is think of this cool title and it catches the person's attention to see your blog. I guess to answer my question it's just for fun or some other reason i didn't think of on why we blog .........and that having no idea on what to think about could end up sometimes becoming the topic of the conversation.