Now most people who give it a simpler definition calls it an online version of a diary or journal that's shared amongst the vast internet community. However I don't think it's a good definition. I rather say it's similiar to a keeping a journal but your not only sharing information or ideas or something you know that can help those around you, but you're getting to know those you reach as well as getting to know yourself. You just happen to keep a log or in this case a "journal" of your happenings and going-ons lol.
Google (see image below) gives a great definition of it in the most simplified way possible. Then I also know many people still aren't sure what the purpose of a blog is. So you document a few tidbits throughout the day or week and post a cute picture your friend shared on Facebook that you like but after awhile I can honestly say once you've covered that, you'll be stumped. I originally started my blog so that I could post my poetry unfortunately that idea fizzled out faster than a firework.How Stuff Works has an interesting article on how blogs work and give a more in depth explanation. While Ask.com gives a short yet detailed definition with a few examples.
For me it was more of a emotional outlet. Nothing too crazy but I talked about what I couldn't talk about with friends or family. I felt better once I released it and moved on. Then I decided why pick one topic when I can do tons of topic?! I post about anything interesting and even things I find throughout the day. Pictures I've loved, inspirational things that uplift me and real stuff that others find inappropriate or too taboo for conversation. I like it better that way. I can keep up with my topics and not fizzle out like I'm writing a term paper.
Since most bloggers in my age group are married or mommies or college graduate traveling gypsies. I bring something unique to the mix. I may not have a ton of followers nor have the recognition like those big name blogs out there (Perez Hilton is a good example) but I'm happy if I reached someone, or made their day or made them feel better about themselves or even let them know that they're definitely not alone in the goofball department and if they ever do feel alone they can come visit me. I'll always have something interesting for them.