Daylight saving time (DST) or summer time is the practice of advancing clocks during summer months by one hour so that evening daylight lasts an hour longer, while sacrificing normal sunrise times. Typically, regions with summer time adjust clocks forward one hour close to the start of spring and adjust them backward in the autumn to standard time. Some countries do not use standard time. For example, the Greenwich meridian passes through France but it does not use Greenwich Mean Time. People use the terms "spring forward" and "fall back" when referring to this.