Greenwich Mean Time (GMT) is a term originally referring to mean solar time at the Royal Observatory in Greenwich, London. It is commonly used in practice to refer to Coordinated Universal Time (UTC).

What does this mean in the forex market?
GMT provides a standard of time for the world when trading the forex market. GMT time does not change for daylight savings time. However, it is important to note that when clocks are pushed forward an hour in the spring, the market opening times change in terms of GMT.

For instance, the New York market opens at 8am Eastern Time (EST) year round. However, throughout the winter months, the New York market opens at 13:00 GMT time. When daylight savings time occurs in the spring, the New York market open changes to 12:00 GMT. (Note: GMT always stays the same. It is the market opening hours that are changing due to daylight savings.)

The following chart shows the forex market hours in eastern time (EST) and GMT.