A migrant worker is someone who regularly works away from home, if they even have a home.
The United Nations' use of this term overlaps with 'foreign worker'. In the United States, the term is commonly used broadly to describe people who move frequently to find work or, more narrowly, those who earn low wages performing manual labor in the agriculture field.
Migrant workers are often forced into poor situations. Some are illegal immigrants and can be expelled if found. They are supported by the International Labour Organization. In 1990, the United Nations also adopted the Convention on the Rights of All Migrant Workers to protect them.
Often migrant workers can boost regional economy by spending their wages there.
Open borders support migrant workers. In Europe for example countries that recently joined European Union have seen massive outflow of workers to the countries with higher wages. Some people who work in foreign countries are called "expatriates"'.