How do record labels promote releases?

Record labels need releases to sell well, in order to encourage this they have to promote the singles/albums as best they can using a range of different media platforms, synergy. Tv and magazine adverts have always been a popular and effective way of doing this. However recently labels have been using other opputunities that are being created as technology improves. They now take advantage of the internet, often encouraging their artists to promote their own releases on social networking, Twitter being a popular way. They also use their websites and pay for coverage on Itunes and HMV websites. They also pay for space on the radio. This is all done as well as traditional ways, such as merchandise and billboards.