Six Types Of Business Blogs - A Classification
Corporate (or Business, Organizational) blogs can be classified into six different categories. Each category shares common characteristics and the blog content can be expected to differ between the categories. Furthermore, there's differences in terms of target groups and purposes.
Even if we also see hybrid forms where blogs are examples of more than one category, an organization that professionally incorporates blogging into its communications strategy will likely prioritize one purpose (for each blog).

At least, that's what I think and suggests. A recent
post and
discussion got me going on this.
Why do we need a classification at all, you might ask. One situation I have in mind is when a corporate communications manager seriously wants to investigate the potential benefits of blogging. Doing that, she could stumble upon so hugely different blogs that nothing would make any sense. But with the help of a filter of some kind - a classification - research and discussion would be much easier. It would also make it less confusing to talk about "blogs" on a general level.
So, this is my idea. Opinions appreciated!
Sales blogs - external Purpose: To market or sell products/services, make citizens aware of public services, get donations for charities or political parties etc.
Blogger: The organization itself, or more specifically individuals within it writing on behalf of the organization.
Target groups: (Potential) clients/customers and citizens, that is persons and/or other organizations that are directly involved with the publishing organization, or those it wants to reach with the purpose above.
Relationship blogs - external
Purpose: To create, uphold or strengthen relationships.
Blogger: The organization itself, or more specifically individuals within it writing on behalf of the organization.
Target groups: Often smaller and more specified than with sales blogs. Examples are support blogs aimed at customers of a certain product, finance blogs for IR purposes, PR blogs for media, blogs trying to reach students, future employees, politicians/officials etc.
Branding blogs - external
Purpose: To strenghten the brand, the profile, of the publishing organization or individuals within it.
Blogger: Not necessarily the organization itself. Individual employees' or executives' blogging ("insider blogs"), if supported by the organization, can be viewed as a branding blog. The same goes for adverblogs and blogs that are not apparantly connected to the organization.
Target groups: See Relationship and Sales blogs.
Knowledge blogs - internal
Purpose: To give employees information and insights relating to their work assignments; news, business intelligence, reports about ongoing projects etc.
Blogger: The organization itself through one or more designated bloggers, or potentially all employees through a entirely open blog publishing model.
Target groups: All employees with a certain interest.
Collaboration blogs - internal
Purpose: To provide a working team with a tool for research, collaboration and discussion.
Blogger: The team.
Target group: The team.
(There's only a fine line - if any - between this blog category and business wiki's. You could also see for example Relationship Blogs change into more wiki-like publications.)
Culture blogs - internal
Purpose: To strengthen organizational culture. Typically through informal content of social or non-work related character.
Blogger: The organization itself through one or more designated bloggers, or potentially all employees through a entirely open blog publishing model.
Target groups: All employees as employees, and not as professionals (developers, managers, assistants and so on).
For the record: I haven't gone crazy. I don't believe we ever will find a classification that all bloggers feel comfortable with. Thankfully there's too many opinions and views for that. Still, the potential corporate blogger would rather have many classifications to lean on than none at all, I think.