"Indel" is an abbreviated term representing a mutation that incorporates both insertions and deletions of contiguous symbols from a genetic string. One reason for lumping insertions and deletions together into a single term is because given two genetic strings for comparison, it is often clear whether a contiguous interval of mismatched symbol corresponded to an insertion of these symbols into one string or a deletion of the same symbols from the other string; compare to the term gap in alignment terminology.