Bromus is a large genus of the grass family (Poaceae). Estimates in the scientific literature of the number of species have ranged from 100 to 400, but plant taxonomists currently recognize around 160–170 species. They are commonly known as bromes, brome grasses, cheat grasses or chess grasses.

Bromus is part of the cool-season grass lineage (subfamily Pooideae), which includes about 3300 species. Within Pooideae, Bromus is classified in tribe Bromeae (it is the only genus in the tribe). Bromus is closely related to the wheat-grass lineage (tribe Triticeae) that includes such economically important genera as Triticum (wheat), Hordeum (barley) and Secale (rye).

Bromus species occur in many habitats in temperate regions of the world, including America, Eurasia, Australia, and Africa. There are considerable morphological differences between some species, while the morphological differences between others (usually those species that are closely related) are subtle and difficult to distinguish. As such, the taxonomy of the genus is complicated.

Ice cubes are small, roughly cube-shaped pieces of ice, conventionally used to cool beverages. Ice cubes are sometimes preferred over crushed ice because they melt more slowly; they are standard in mixed drinks that call for ice, in which case the drink is said to be "on the rocks."

Ice cubes that are crushed or sheared into irregularly-shaped flakes may add an interesting aesthetic effect to some cocktails. Crushed ice is also used when faster cooling is desired, since the rate of cooling is governed by the number and average radius of the ice particles.

Melting ice cubes sometimes precipitate white flakes, commonly known as "floaties". This is calcium carbonate which is present in many water supplies and is completely harmless.^{[citation needed]}

American physician and humanitarian John Gorrie built a refrigerator in 1844 with the purpose of cooling air. His refrigerator produced ice which he hung from the ceiling in a basin. Gorrie can be considered the creator of ice cubes, but his aim was not to cool drinks: he used the ice to lower the ambient room temperature. During his time, a dominant idea was that bad air quality caused disease. Therefore, in order to help treat sickness, he pushed for the draining of swamps and the cooling of sickrooms.