Selection of advertisements for placement with content

A computer-implemented method comprising:

• receiving a request for sponsored content for presentation with a content item, wherein the content item is included in a document;
• for each of one or more candidate sponsored content items:
• calculating a first score based on, at least, a comparison of the candidate sponsored content item to one or more keywords for the content item;
• calculating a second score based on, at least, a comparison of content one or more second documents that link to the document to the candidate sponsored item;
• calculating a final score based on, at least, a combination of the respective first and second scores;
• selecting one or more of the candidate sponsored content items based on, at least, the candidate sponsored content item's respective final score;
• and
• providing the selected sponsored content items for presentation with the content item.

A system comprising:

• data processing apparatus programmed to perform operations comprising:
• receiving a request for sponsored content for presentation with a content item, wherein the content item is included in a document;
• for each of one or more candidate sponsored content items:
• calculating a first score based on, at least, a comparison of the candidate sponsored content item to one or more keywords for the content item;
• calculating a second score based on, at least, a comparison of content one or more second documents that link to the document to the candidate sponsored item;
• calculating a final score based on, at least, a combination of the respective first and second scores;
• selecting one or more of the candidate sponsored content items based on, at least, the candidate sponsored content item's respective final score;
• and
• providing the selected sponsored content items for presentation with the content item.

A program product stored on a machine readable storage medium that, when executed by data processing apparatus, causes the data processing apparatus to perform operations comprising:

• receiving a request for sponsored content for presentation with a content item, wherein the content item is included in a document;
• for each of one or more candidate sponsored content items:
• calculating a first score based on, at least, a comparison of the candidate sponsored content item to one or more keywords for the content item;
• calculating a second score based on, at least, a comparison of content one or more second documents that link to the document to the candidate sponsored item;
• calculating a final score based on, at least, a combination of the respective first and second scores;
• selecting one or more of the candidate sponsored content items based on, at least, the candidate sponsored content item's respective final score;
• and
• providing the selected sponsored content items for presentation with the content item.