This is a very complete introduction to migraine, and it has surprisingly few ads or distractions.

If you click at the top on the Migraines overview it provides a very good overview of migraines. The page this links to is almost like an index (nothing really provided besides links). Since we are rating this page I'm going to go down the middle again. I personally think it might have been better to use the link to the Migraines overview page rather than this index page as it provides tons of information, but I can understand why they might put an index page here as well. I highly suggest the Migraine Overview and would give that link itself a 5.