System file used by Index Server, a component of the Windows operating system used for searching; saved in a plain text format and contains a list of noise words, which are keywords that are excluded from the search indexing process; located in the C:\Windows\System32\ directory and has the filename NOISE.CHS; used for the Chinese (CHS) noise-word list in Windows.

CHS files help Windows speed up the process of indexing by removing words that would only create unwanted "noise" in the search results. Example noise words include "the," "or," "it," and "this." An example Chinese noise word in the Windows CHS file is 的, which means "of."