Exact pronunciation of "word acronyms" (those pronounced as words rather than sounded out as individual letters) often vary by speaker population. These may be regional, occupational, or generational differences, or simply a matter of personal preference. For instance, there have been decades of online debate about how to pronounce GIF ( or ) and BIOS (, , or ). Similarly, some letter-by-letter initialisms may become word acronyms over time, especially in combining forms; "IP" for "Internet Protocol" is generally said as two letters, but "IPsec" for "Internet Protocol Security" may be pronounced as or , with the latter increasing over time (along with variant spellings like "IPSEC" and "Ipsec"). Pronunciation may even vary within a single speaker's vocabulary, depending on narrow contexts. As an example, the database programming language SQL is said as three letters in most cases, but in reference to Microsoft's implementation is traditionally pronounced the same as the word "sequel".