19. The method of claim 13 , comprising: receiving input, by the interface over the computer network, corresponding to an addition, deletion, or change to a keyword of the second plurality of keywords; calculating, by the one or more processors responsive to a request for content, a second keyword score for each of the second plurality of keywords of the content item, the second plurality of keywords updated based on the input corresponding to the addition, deletion or change; and selecting, by the one or more processors, based on a comparison of each of the second keyword scores, a different one and only one of the second plurality of keywords for the content item.
20. The method of claim 19 , comprising: calculating, by the one or more processors, the second keyword score based on one or more web pages selected by a publisher, by a user interface.