Thumbnails:Forensic computer terms A thumbnail image is a miniature display of a picture. These are commonly associated with web pages which when selected bring up a larger version of the same picture as a link. Thumbs.db is an artifact of the Microsoft Windows operating system which serves to catalog all image files which have been viewed using the thumbnail view of Windows Explorer. Windows creates this file so it can display the thumbnails faster the next time the user views the contents of the folder in Windows Explorer. Since the thumbs.db files contain copies of the thumbnails, these copies persist within the thumbs.db file even after the original graphics files are deleted.