Flagstone is one of the best materials for patios primarily due to its narrow packed joints that allow water to permeate instead of running off. Flagstone patios also have a very natural, organic look due to their shape and earthy shades of browns, reds, grays and blues. The most common types of flagstone used for paving patios are sandstone, slate and limestone. Flagstones can be used to create a formal or informal patio. For a formal look, select cut flagstones and have them laid in a repeating pattern. For an informal look, select irregular flagstones and have them laid randomly. This informal style is often called crazy paving. Flagstone provides a durable and naturally slip-resistant patio surface that will last for years.