Trilogy of social media

I have been meaning to blog about my opinion of social media for a while now.  For all intents and purposes of this blog there are only three social media sites that actually exist.  The hundred thousand others sites are a mediocre shot at what these three have accomplished.  The three I am referring to are, Linkedin, Facebook, and Twitter. Founded in 2003, 2004, 2006, respectively, they have become the “trilogy of social media.”  I refer to them as a trilogy for no other reason than they were founded in different years, and they have become the leaders in social media.  I have decided to do lists of “Pros” v “Cons” for my opinion.

1. Easy setup
2. simple layout
3. group pages are educational
4. recommendations are cute
5. earn about local competition
6. offers everyone a seat in the social media game

1. is a lame attempt at networking
2. name me one person who has actually finished the interview process
3. over saturated
4. groups are poorly monitored
5. offers everyone a seat in the social media game

Facebook:
Pros:

1. connects friends and relatives
2. easy to use
3. customize-able

Cons:

1. Security
2. gateway to a porn addiction
3. 500 million…seriously?

Twitter:
Pros

1. Collaboraters playground
2. Separates the adults from the children of social media
3. Advanced search to RSS is powerful (thanks Dustin)
4. Barrier to entry, more difficult than the other two
5. Content/links are meaningful

Cons:

1. Days can elapse while reading tweets.
2. Super spammers

Care to add any?