Albert Lennon wisely says metadata is "data about data".
This is the stuff Google loves. More specifically its the Googles search engine robots that love this metadata. As it feeds them the info they crave to make decisions.
The decision specifically that the Google bots make is “is this image relevant?”.
Relevance is everything for Google. Its how it sorts out which sites make it to the top of a Google search, as oppose to which linger in the dead zone – Google search page 2 and beyond.
So add metadata to every image on your web site! How? Ill show you two ways:
1. In Photo shop: Go to File> File Info, to bring up the metadata dialog box. Add as much data as you can here. For example in the Description box add a catchy sentence as you would speak it to another human. Then below this in the keyword section add keywords separate by commas, as you would speak to a robot. Save the file. Now when you export you image the metadata will be included in the image.
2. To take this to the next level now open you image in Adobe Bridge. You will see the Keywords and Metadata tab on the lower right. Add away! You file is now fully packed with metadata to give it extra punch on Google.