Windows Indexing Service

The Windows Indexing Service catalogues the contents of your hard disk, and even the contents of files, to make local searching faster. This service creates and later consults a number of small databases containing data about your disk's contents, including the actual contents of files, which can undermine the practice of good data hygiene. Indexing creates what amounts to a scattered secondary volume of your data, and your wipe utility might fail to erase all these related traces when it erases a file.

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