What is PDT, Pst us time

I often see information on the Internet such as "AM, PDT" from 09-4-18. What is PDT?

PDT isPacpacific Daylight Time Pacific summer time. The west coast of the United States (San Francisco, Los Angeles, Portland) used this time in the daylight saving time.

The U.S. summer begins with the first Sunday of 1st every year and ends with the last Sunday of every year. The renewal time is one hour earlier than the normal time.

Corresponding to PST, Pacific Standard Time. It is PST after the daylight saving time.

PST is the standard time in the Pacific Ocean (West 8). It has a time difference of-16 hours from Beijing Time (UTC + 8), that is, Beijing time minus 16 is the PST time. PDT is one hour earlier than PST, that is, the time difference between PDT and Beijing is-15 hours.

The United States spans the West five to the west TEN, a total of six time zones. Each time zone corresponds to a standard time, from the east to the west are the eastern time (EST) (West five district time), the Central Time (CST) (West six district time), the Mountain Time (MST) (west seven time), Pacific time (West time) (PST) (West eight time), Alaska time (akst) (West Nine time) and Hawaii time (HST) (Time in the Tenth District of the west), according to the rule of "east, west, and evening", each decreases by one hour.

US standard time	Time Difference from Beijing time (hours)
HST	-18
Akst	-17
Pst	-16
MST	-15
CST	-14
EST	-13

The summer begins on the first Sunday of 1st every year, and ends on the last Sunday of every year. Also known as DST: Daylight Saving Time ..

U.S. summer time	Time Difference from Beijing time (hours)
HDT	-17
Akdt	-16
PDT	-15
MDT	-14
CDT	-13
EDT	-12