Short answers, pulled from the story.
A riot is a form of civil disorder in which people commit public violence against government, other authority figures, or property. It typically involves destruction of public or private property, such as shops, cars, restaurants, state-owned institutions, and religious buildings.
Riots often occur in reaction to a grievance or out of dissent. Historical causes include poverty, unemployment, poor living conditions, governmental oppression, taxation, conscription, conflicts between ethnic groups or religions, and the outcome of a sporting event.
Types of riots include food riots, police riots, political riots, prison riots, race riots, religious riots, and sports riots. In a race riot race or ethnicity is the key factor, while in a religious riot the key factor is religion, and food riots arise from food shortages.
During the 1992 Los Angeles riots, 2,383 people were injured, more than 12,000 were arrested, 63 people were killed, and over 700 businesses burned. Property damage was estimated at over one billion dollars, and at least ten of those killed were shot by police or National Guard forces.
Police often use tear gas or CS gas, and less-than-lethal methods such as flexible baton rounds, rubber bullets, water cannons, attack dogs, pepper spray, and snatch squads. Many forces maintain dedicated public order divisions, such as the Territorial Support Group in London and the Compagnies Républicaines de Sécurité in France.
Riot is a statutory offence in England and Wales under section 1(1) of the Public Order Act 1986, requiring 12 or more persons present together using or threatening unlawful violence for a common purpose. It is an indictable-only offence, and a person convicted is liable to imprisonment for any term not exceeding ten years, or to a fine, or to both.