Daylight saving time
Also summer time in several countries including in British English and European official terminology.
By the Energy Policy Act of 2005, daylight saving time (DST) was extended in the United States beginning in 2007. DST currently starts on the second Sunday of March, which is three or four weeks earlier than in the past, and it ends on the first Sunday of November, one week later than in years past. The time is adjusted at 2:00 a.m. (02:00) local time.
Year DST Starts DST Ends
2010 March 14 November 7
2011 March 13 November 6
2012 March 11 November 4
2013 March 10 November 3
Time zones within the United States are:
Time Zone Standard Time Daylight Saving Time
Eastern Time Zone EST (UTC-5) EDT (UTC-4)
Central Time Zone CST (UTC-6) CDT (UTC-5)
Mountain Time Zone MST (UTC-7) MDT (UTC-6)
Pacific Time Zone PST (UTC-8) PDT (UTC-7)
Alaska Time Zone AKST (UTC-9) AKDT (UTC-8)
Hawaii-Aleutian Time Zone HAST (UTC-10) HADT (UTC-9) *
UTC-Coordinated Universal Time
Source Initials Words
English CUT Coordinated Universal Time
French TUC Temps Universel Coordonné
compromise UTC unofficial English: "Universal Time, Coordinated"; unofficial French: "Universel Temps Coordonné"
The 12-hour clock is a time conversion convention in which the 24 hours of the day are divided into two periods[1] called ante meridiem (a.m., English: "before midday") and post meridiem (p.m., English: "after midday").
The Latin abbreviations a.m. and p.m. (often written "am" and "pm", "AM" and "PM", or "A.M." and "P.M.") are used in English and Spanish.[7] The equivalents in Greek are π.µ. and µ.µ., respectively. China-24-hour clock. The 12-hour clock is the dominant system of time written and spoken in U.S.A.