Well-written technical documents usually follow formal standards or guidelines. Technical documentation comes in many styles and formats, depending on the medium and subject area. Printed and online documentation may differ in various ways, but still adhere to largely identical guidelines for prose, information structure, and layout. Usually, technical writers follow formatting conventions described in a standard style guide. In the US, technical writers typically use The Associated Press Stylebook or the Chicago Manual of Style (CMS). Many companies have internal corporate style guides that cover specific corporate issues such as logo use, branding, and other aspects of corporate style. The Microsoft Manual of Style for Technical Publications is typical of these.