19. A system for incrementally identifying and selecting a television content item to be presented from a relatively large set of selectable television content items, the television content items being associated with descriptive terms that characterize the selectable television content items, the system comprising: a database in an electronically readable medium for storing the relatively large set of selectable television content items and associated descriptive terms that characterize the selectable television content items; a plurality of subsets of television content items, each subset being ranked and associated with corresponding strings of one or more descriptive prefix strings based on an ordering criteria, each descriptor prefix string being a variable length string containing a subset of the characters of the descriptive terms that characterize the selectable television content items, wherein each descriptor prefix string contains less than all characters of the descriptive terms; and program code on a computer-readable medium, which when executed on a computer system performs functions including: receiving incremental text input entered by a user, the incremental text input including a first descriptor prefix of a word entered by the user for incrementally identifying at least one desired television content item of the relatively large set of television content items, wherein the first descriptor prefix contains less than all characters of the word the user is using to incrementally identify the at least one desired television content item; selecting and presenting on a display device the subset of television content items that is associated with the first descriptor prefix string; subsequent to receiving the first descriptor prefix, receiving subsequent incremental text input entered by the user, the subsequent incremental text input including a second descriptor prefix of a word entered by the user for incrementally identifying the at least one desired television content item and forming a string of prefixes including the first descriptor prefix and the second descriptor prefix in the order received, wherein the second descriptor prefix contains less than all characters of the word the user is using to incrementally identify the at least one desired television content item; and selecting and presenting on the display device the subset of television content items that is associated with the string of prefixes received.
31. The system of claim 19 , wherein the descriptive terms are determined by identifying a set of candidate terms comprising ordered or unordered words.