One or more techniques and/or systems are disclosed for matching a target string to a known string. A target string is broken into one or more target terms, and the one or more target terms are matched to known terms in an index tree. The index tree comprises one or more known terms from a plurality of known strings, where the respective known terms in the index tree are associated with one or more known string IDs. A known term that is associated with a known string ID (in the index tree, and to which a target term is matched), is comprised in a known string, which corresponds to the known string ID. The target string can be matched to the known string using the known string's corresponding known string ID that is associated with a desired number of occurrences in the matching of the one or more target terms.