Is immigration the biggest issue of our time? On both sides of the Atlantic, immigration protests have erupted into violence. It seems to provoke more passion than almost any other issue.
Two cities. Two migrant protests spiral
Contrasting scenes: Pro-immigration demonstrators gather in Los Angeles, while Northern Ireland experiences violent unrest believed to have been sparked by anti-immigrant anger. Glossary
Metropolis - A very large and busy city.
Immigration - The permanent movement of people into a country.
Customs - The tax a country takes from imported goods.
National Guard - Part of the USA's military reserve.
Misinformation - Incorrect or misleading information unintentionally presented as fact. It can be contrasted with disinformation or deliberate lies.
Far-right - A range of ideologies that emphasise social order, racial purity and the elimination of opponents.
Left-wing - A range of beliefs that are the opposite of right-wing ideas. People on the political left usually believe in collective responsibility and the good of society. They often, though not always, support higher taxes and a more active, interventionist government.
Labour - Britain's main left-of-centre political party.
Polarisation - When people tend to flock towards extreme opposite points of view. Some think that polarisation is bad for politics, because it makes co-operation between people on opposing sides of a debate less likely. Others welcome it, however, because it offers voters clear alternatives in elections.