This typing lesson will teach you the [ and ] keys. These keys are know as "square brackets" and are used extensively in some programing languages to denote an item's position in an array. Square brackets are also common in articles where text has been added to clarify the original author or speaker's intent, such as clairfying who he, or what it is. They are also used for footnotes or to indicate mistakes in original copy [sic]. If you already know the keyboard, try our our programming drills or symbol drills for more relevant practice exercises.