UTC-4 is a time zone that is four hours behind Coordinated Universal Time (UTC). It is commonly used in regions such as the eastern part of Canada, parts of the Caribbean, and some areas in South America. During standard time, places like Atlantic Standard Time (AST) and Eastern Daylight Time (EDT) observe this offset. When daylight saving time is in effect, some regions switch to UTC-4, allowing for longer daylight in the evenings. This practice is observed in areas like New York and Toronto during the summer months, enhancing outdoor activities and energy efficiency.