Pacific Standard Time (PST) is a time zone that is 8 hours behind Coordinated Universal Time (UTC-8). It is primarily used in the western part of the United States and Canada, including states like California, Washington, and Oregon. PST is observed during the fall and winter months, typically from the first Sunday in November to the second Sunday in March. During the rest of the year, these regions switch to Pacific Daylight Time (PDT), which is UTC-7. This change helps to make better use of daylight during the longer days of summer. The transition to and from PST is part of the broader practice of Daylight Saving Time.