There is a pretty long arc to this story, and it seems to be shaking out this way:
The Internet and web start to become popular, circa 1995, and all travel agents and airlines and hotels are scared by this new technology.
Not to treat the matter with any disrespect at all but only in a cold, factual historical way, 9/11 happens - and all the travel people who had any reservations about their fares. rates, etc. being seen/distributed/sold on-line throw all their inventory on at the big travel websites (Expedia, Travelocity, etc.). Air and hotel.
This works for a while, but some slowly start to take inventory away/cut commissions, etc. as they learn they can offer all this stuff on their own websites, with the best price sometimes, and still make a lot more per sale than having to pay a commission to a third party.
Then the world financial crisis hits in 2008, and everything goes on sale again, etc.
The world economic situation stabilizes (though I know it is still crap for many of us!), more airlines consolidate, the airline industry cowers that Google may control it by buying the largest back end provider (a story you should know -
http://www.washingtonpost.com/wp-dyn/co ... 02817.html announced in July 2010 it is still ongoing and the industry is very against it), and airlines especially start to take back their inventory, realizing (maybe hoping) that they don't need the distribution of the big sites like Expedia etc.
Frankly this industry is a mess but it seems like it always has been. Hotels are still in terrible shape statistics wise - occupancy rate in the U.S. in 2010 was something like 36% - 2 out of 3 rooms empty every night! And revenue per rooms is just starting to recover a bit.
Anyway - here is a NY Times article about the airlines with some good tips:
http://www.nytimes.com/2011/01/08/travel/08air.html