On the Web
A blog is basically a journal that is available on the web. The activity of updating a blog is "blogging" and someone who keeps a blog is a "blogger." Blogs are typically updated daily using software that allows people with little or no technical background to update and maintain the blog.
A blog is usually a publicly accessible personal journal for an individual. Similar to a personal diary, but shared over the web. One advantage of sharing thoughts and reflections with others especially friends – is that they can comment, offer advice, help, good suggestions etc.
Blogs can contain links to good websites and other web based materials, which can make them a very rich source for later reflection. And ..because they are on the Web, students can post your reflections at any time and from anywhere.