The term 'insertion symbol' can refer to a caret, which is a symbol (^) used in writing and editing to indicate where text should be inserted. It is commonly used in computer programming and other coding languages to denote the beginning of a line or command. The caret is also used in mathematics to indicate an exponent or superscript. In some contexts, the caret is referred to as a 'HAT' or 'ROOF' symbol.