A cluster bomb unit or CBU is a type of weapon that releases dozens or even hundreds of smaller bomblets over a wide area to create maximum damage. As these weapons are often considered controversial, there are several synonyms used to describe them. These include cluster munitions, bomb clusters, bomblets, and submunitions. Other synonyms that are often used to describe these types of weapons include scatter bombs, area denial munitions, and anti-personnel munitions. While these weapons can be highly effective in certain situations, they are also responsible for causing a considerable amount of collateral damage, and many countries around the world have taken steps to ban or restrict their use.