How many companies use Google AdWords?

I hear about a lot of advertising companies using an "adwords" model.  What are some examples?  How are they different?

There seems like a lot of companies doing,  one that looks attractive is retargeter.com due to entry cost but why would I use that versus simply using the integrated functionality from Google AdWords?  Is Google missing some features?

This seems like a stupid question to me, but whatever is going wrong for me seems like it should be a common problem.  I am trying to use Google Adwords new Reviews extension.  We have lots of good reviews that were on the Google Places/Google+ Local...

How does Google charge for use of its Adwords API tool when using it to import keyword search volume into Google docs? I sifted through a fair bit of documentation, but didn't get their system for charging for data use. For example: - Is there a specific...

I have a little notification on my videos page saying (Grow your audience create a campaign on adwords for video to promote your videos. Get started here). I was wondering should i do this? Will this help me like earn more subs/views/money etc for adsense...

I am working on a new startup that helps connect customers of big companies with people inside the companies to help them deal with customer support and cut through red tape.  I think this is a legitimate claim to being an informational site, which Google...

There's a tendency at Google to write in-house software for our unique scaling needs (both engineering/software processes and hardware). A good number of these have been open sourced and made available to the developer community as well, the likes of...

Google Adwords is the cash cow of Google.  However, the UI for adwords (where you build ads, select keywords and manage your spending) is very confusing.  Clearly there is a large team working at this, and they must have been working on it for nearly...