1. A computer implemented method, comprising: receiving search request data specifying a search request, the search request comprising a drawing represented by a set of line strokes, wherein each line stroke represents a trace of a moving input point; identifying line segments from the line strokes in the set; comparing the identified line segments to reference line segments, wherein each of the reference line segments represents a portion of a corresponding reference drawing; identifying, by one or more data processors, a candidate reference drawing based on the comparison of the identified line segments with reference line segments representing the candidate reference drawing; identifying a keyword for the candidate reference drawing, wherein the keyword is a term determined to be relevant to a subject matter of the candidate reference drawing; in response to receiving the search request data, providing search results data specifying search results responsive to the keyword; identifying multiple keywords for the candidate reference drawing; providing the multiple keywords for the candidate reference drawing for selection on a search results page; receiving user selection of a particular one of the multiple keywords that are provided for selection on the search results page; and performing a search using the particular one of the multiple keywords in a search query in response to user selection of the particular one of the multiple keywords.