Meta Tags in Drupal - Making the right decision for your Drupal website
Recently while doing some maintenance work on some of our websites, I noticed that there were robots=noindex,nofollow tags in page head! This was a result of us overlooking the changes that resulted from an upgrade of the nodewords module. You can imagine the impact this had on our sites.
Here's a quick look (<15min) the most important role meta tags play in websites, and which module to use for that purpose.