Way back when overture came up with pay per click advertising, a trend started. Lot of search engine companies introduced the PPC program. But they could not make it impressive. However Google with their adsense program get hold of the market. As their search engine was most popular, they captured the market quite easily. The need for an AdSense alternative continues to grow. Based on the market response Yahoo launched their contextual advertising program. MSN will also be starting their program. Until recently, there hasn't really been a decent alternative to AdSense.
