A Blog is like an online journal, the user can update it whenever they like. A wiki is a website that has a group of users that can all the change the website, wiki's are good to use for school work so the teacher can assign you a page and you can put your stuff on it so nothing goes missing, some of the bad things about blogs and wiki's is that almost everyone would be able to see your work of journal type thing if you put it on the internet so a blog is probably not the best idea for very personal things, its better for just basic life story, overall i think there a pretty good idea but there are some few crap with them.