The terms upper case and lower case can be written as two consecutive words, connected with a hyphen (upper-case and lower-case), or as a single word (uppercase and lowercase). These terms originated from the common layouts of the shallow drawers called type cases used to hold the movable type for letterpress printing. Traditionally, the capital letters were stored in a separate case that was located above the case that held the small letters, and the name proved easy to remember since capital letters are taller. 

The convention followed by many British publishers (including scientific publishers, like Nature, magazines, like The Economist and New Scientist, and newspapers, like The Guardian and The Times) and U.S. newspapers is to use sentence-style capitalisation in headlines, where capitalisation follows the same rules that apply for sentences. This convention is usually called sentence case. It may also be applied to publication titles, especially in bibliographic references and library catalogues. Examples of global publishers whose English-language house styles prescribe sentence-case titles and headings include the International Organization for Standardization.
What titles might it be applied to?
also be applied to publication titles