Code Pages

https://docs.microsoft.com/en-us/windows/desktop/intl/code-pages

Most applications written today handle character data primarily as Unicode, using the UTF-16 encoding. However, many legacy applications continue to use character sets based on code pages. Even new applications sometimes have to work with code pages, often for one of the following reasons:

To communicate with legacy applications.
To communicate with older mail and news servers, which might not always support Unicode.
To communicate with the Windows Console.

Note

New Windows applications should use Unicode to avoid the inconsistencies of varied code pages and for ease of localization.

Each code page is represented by a code page identifier, for example, 1252, and is handled by the Unicode and character set API functions. For a list of supported code page identifiers, see Code Page Identifiers. The "Code Pages" reference on the Microsoft Go Global Developer Center gives full descriptions of many code pages.

Windows code pages, commonly called "ANSI code pages", are code pages for which non-ASCII values (values greater than 127) represent international characters. These code pages are used natively in Windows Me, and are also available on Windows NT and later.