A directive to a performer to smoothly increase the volume of a particular phrase or passage. This can be designated with the word crescendo at the beginning of the passage or with the crescendo symbol consisting of two horizontal lines that start together at a point at the left and spread apart to the left. There is typically a dynamic mark at either end of the symbol indicating the desired volume before and after the crescendo. This is often seen in its abbreviated form cresc.. The symbol is often refered to as a hairpin or a wedge.