I don’t know myself, but the hit website “Wikipedia” says:
“Grass is a plant with narrow leaves growing from the base. A common kind of grass is used to cover the ground in places such as lawns and parks. Grass gets water from the roots in the ground. Grass is usually the colour ‘green’. Grasses are monocotyledon, herbaceous plants.

The grasses include the “grass”, of the family Poaceae (also called Gramineae). Sometimes it is also used to include the sedges (Cyperaceae) and the rushes (Juncaceae).[1] These three families are not closely related but belong to different clades in the order Poales. They are similar adaptations to a common life-style.

The true grasses include cereals, bamboo and the grasses of lawns (turf) and grassland. Uses for graminoids include food (as grain, sprouted grain, shoots or rhizomes), drink (beer, whisky), pasture for livestock, thatching thatch, paper, fuel, clothing, insulation, construction, sports turf, basket weaving and many others.

Many grasses are short, but some grasses, like bamboo, can grow very tall. Plants from the grass family can grow in many places, even if they are very cold or very dry. Several other plants that look similar but are not members of the grass family are also sometimes called grass; these include rushes, reeds, papyrus, and water chestnut.”