Adsense Portal

Until now advertisers had the option of asking Adsense to place their ads on a specific site. This feature was known as site targetting. Now advertisers also have the choice of displaying ads according to the channels you have provided.
When you try to create a new custom channel there will be an option "Targeting: Show this channel to advertisers as an ad placement". By checking this option you can allow the advertisers the option of just targetting specific channels on your site. This can only work for custom channels, not for url channels. The advertiser can see the name of your channel. So it is important that the name you give to the channel is descriptive. If you want to allow targetting for a pre-existing channel the process is as follows:

1. Log into your account at http://www.google.com/adsense
2. Under the AdSense Setup tab, visit the Channels page.
3. Under the AdSense for content subtab, make sure you've selected custom channels.
4. Click the radio button next to the channel you'd like to make targetable, then click the corresponding 'edit settings' link.
5. Click the checkbox marked 'Show this channel to advertisers for targeting' and enter a description for your channel. Keep in mind that advertisers will see the name and description, so you want to provide something accurate and informative that will represent your site well.
6. Click 'Save channel'.

With this feature advertisers have the option of placing ads wherever they want to on your page. As most people create seperate channels for their ad units, advertisers can determine where their ads will be placed.