A suffix that is preceded by a decimal (".") and that is appended to a computer file name. Note: Common filename extensions with their meanings are:
.wpd = a type of word-processing document
.doc = a type of word-processing document
.exe = executable code or a self-extracting archive file.
.gif = a graphical interchange format (graphics file)
.txt = a text file.
2. Proprietary HTML tags that are recognized by a single Web browser or by those Web browsers developed by a single company.