.FID File Extension
File Type 1File Expander Engine Descriptions Database
What is a FID file?
Database referenced by File Expander, a file and data objects analysis program; contains descriptions of file formats supported by File Expander; named "FIEngine.fid" by default; also used by the File Investigator SDK.
File Type 2Microsoft Catalog Indexing Service File
.FID File Association 2
System file created by Indexing Service, a Microsoft Windows operating system component that creates a searchable index of file system information; contains data that helps the operating system perform searches more quickly.
FID files are commonly located in the C:\System Volume Information\catalog.wci\ directory.