- The simplest use of a blog is as a "web log" , in other words, a record (on the web) of things you do/encounter/experience.I believe this is how blogs were initially used .Entries like "I went out for dinner with X today and later popped in to see the X-Men movie. The movie was fun" or "Guitar class was tough . I just can't get the finger shift for CMajor-Bminor" belong to this category. This type of blog combines the record keeping benefits of an activity log with the publishing capability of the Internet. Thus the blogger's community of friends can keep track of what is happening in his life. An interesting variant of this is where people blog about the arrival of a baby , detailing information about doctor visits and ultra sound scans, all the way to photos of the various stages of the baby's growth("hey my baby looked at me today. wow! here's a photo".) Yet another variant is a project blog with entries detailing the progress (or otherwise) of a project and is often used in the open source community .
- The second common way to use a blog is as commentary . The mode of posting used here is that of a critic or reviewer , passing judgement on things that interest him .Essentially each post is a review of a movie or book or piece of software, or a court judgement , or anything else that is of interest to the blogger .My friend ,for instance, asked if a chapter by chapter review of the Sanskrit to Malayalam translation of the Ramayana would make a good blog entry . The answer is "yes" .
- The third way is to use a blog as a forum for thinking about ideas or distilling experience .This is essentially the above two forms of blogging plus the recording of extrapolatory thinking.In other words, various things that strike the blogger's interest are logged and then there is an additional facet of thinking about them .It is taken for granted that such thinking is incomplete . For example I learn about the Theory of Constraints and the three main metrics it uses (Throughput, Inventory, and Operational Expense) .I might write a blog entry just applying the idea to a software consulting company and trying to extrapolate a bit ("ok , so applying TOC to software, a programmer on the beach is Operating Expense. So are all the non billable managers, recruiting staff etc. Code written but not paid for is Inventory .Or is it ?If the customer doesn't pay can this code be re used or sold? If not then is that too Operational Expense?" etc.Note the theme of "thinking out loud". The blogs of most software developers have this quality.A commenting facility and a strong community of readers adds an extra dimension to such blogging if they help you to flush out inconsistencies in your thinking and/or add new ideas .
- Another way to use a blog is as a forum for writing/thinking. The blogger sees himself as an author and a blog posting is treated as a literary form just like a magazine article or an essay .In this world view a blog entry is for very short pieces of writing which are not long enough to make it ento an essay or article. Martin Fowler's blog is an excellent example . The main difference from the "exploratory" mode above is that the final piece of writing is much more polished and definite for all its (comparitively) small size. Any thinking is done outside the blog entry itself.Comments may or may not be present (just as there are essays and articles without commenting in books and magazines). This type of blog is used by professional writers or thinkers (management consultants etc) where the blog is additional evidence of the writer's expertise and thus is more "professional" than the "exploratory" or "logging of personal experience" type blogs.
- The fifth way of using a blog is to explicitly focus on building a community and sharing of thoughts within an interest group , something like a distributed news group . Thus you have "java blogs" or "home schooling blogs" . The additional concept here is that the size and quality of the community built up around a blog , with the number and quality of comments, trackbacks and pingbacks is a key metric of how successful a blog is .
In this school of thought (which i don't subscribe to , by the way) a blog is primarily a community building tool, which enables you to reach out and connect to people who share your interests but are distributed across the world. A variant of this is to use a blog to evangelize a particular company or product.Taking this even further, there is the notion of competing with other bloggers for "ranking" in the blogosphere ( a fancy term for "all the world's blogs" ) .
There are people who are professional bloggers and make huge amounts of money from their blogs , either through running ads on their blog sites, getting book contracts, or being sponsored by companies.
- There is an associated concept of "corporate blogging" , that treats blogs as a new medium of communication between the various stakeholders of a company (employees, shareholders etc) . when you hear of someone being fired for "inappropriate blogging", or a company exposing a corporate blog for potential cutomers to know how cool it is, this is the facet at work. There is also a whole ecosystem of visionaries, consultants and snake oil salesmen(not all mutually exclusive) who try to sell blogging tools (often just jazzed up versions of freely available blogging tools priced fantastically to make them "enterprise" worthy ) to bewildered managers as the next silver bullet that will solve all corporate ills.
I guess it just shows I am more of an "anti social element" than he is :-). But then this is not static either. I created this new blog explicitly because many people asked for commenting facilities .So maybe in a year or so I might focus on "community".Right now , for me , a blog is a combination of log of events(minor focus), an arena for exploring thoughts(major focus) and practicing writing(major focus) .