This may be a new kind of question for you. I was also confused about that. Today millions of blogs are now online some of them hosted on fr...

This may be a new kind of question for you. I was also confused about that. Today millions of blogs are now online some of them hosted on free blogging platform while some of blogs on self publishing platform. Most blogs are primarily textual, although some focus on art (Art blog), photographs (photo blog), videos (video blogging), music (MP3 blog), and audio (podcasting). Micro blogging is another type of blogging, featuring very short posts. The Blog may be of following five types.

Types of Blogs [Conventional]

Textual Blogs
Photo Blog
Text + Photo Blog
Video Blog
Text + Photo + Video Blog

Advance Types of Blogs

Audio Blog (podcasting)
Micro blog

As I know in year 2007 Technorati was indexed more than 112 millions blogs now you can imagine this number at present. It means that more and more people are starting blogging. The blogs can be categorized in following categories.

Categorization of Blogs:

Personal Blogs
Corporate and organizational blogs
By genre
By media type
By device

Today most of blogs using the "Text + Photo" blogging types, while some of other advanced blogger are using "Text + Photo + Video Blogging". I also even yet running "Text + Photo" types "Personal blogs".

The Video blogging rising rapidly after the popularity of You Tube, However there are several advantages and disadvantages of Video Blogging.

Easy To understand
More Subjective
Reliable for visitor
Convenient
Reduce Time

However there are several disadvantages of Video blogging also

Need extra equipment (Video Camera etc..)
Very poor over SERP
Can't be viewed by Slower internet connection users
You need to self publish your blog because free blogging platform like blogger have size limit for videos.
Language Problem (In Text blogging reader can change the post language but in video blogging it is not possible)

In short the combination of all say, Text, Images and Videos are advisable to be a good blogger. Share what types of blog and under which category you are running.