.BK2 file extension is a type of Windows Indexing Service Data File; initially developed and managed by Microsoft Corporation. The primary task of BK2 file extension is to index and store the system information for operations like searching and many more. The data that gets indexed in this file format most often stays in the text form. The complete set of information that gets indexed; at a latter end get saved to a catalogue that can be referenced at any point of time.
The .BK2 file extensions fall under the category of System Files.
The .BK2 file extensions are a type binary file format.
The default location of BK2 file extension is C:\System Volume Information\catalog.wci\
The BK2 file can be open and view in Windows Operating System depends on which version it belongs.