OverviewExtensions
An extension is the part of a filename that is used to indicate what kind or "type" of data is contained within a file.
A file extension consists of a period (.) followed by one or more characters at the end of a filename. Windows uses the file extension to determine what kind of information is contained in a file. For example, in the filename myfile.txt, .txt is the file extension that identifies myfile.txt as a text file.
Tip: When reading filenames out loud, the period in the extension is usually pronounced "dot." So myfile.txt would be pronounced "myfile dot text" or "myfile dot tee ex tee."
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