Normally, when the Directory Server conducts a search, the server looks through the entire entry for a match, throughout the entire directory. For large directories, this can slow down searches. Virtual list views (VLV) are a way of indexing entries only by certain attributes, like common name or DN, and then only returning those attributes in the search. When the server does a search, it looks through this list of entry names, which is faster than searching through every entry, especially for directories with 1000 or more entries. This is a "virtual" list because the truncated entry doesn't actually exist.