"Sun, 18 Jan 1970 18:27:20"
Convert date and time to unixtime.
Another datetime format string at UTC
YYYYMMDD
19700118
Only TIME
18:27:20
General datetime
1970-01-18 18:27:20Z
For Database
1970-01-18 18:27:20
For HTTP1.1
Sun, 18 Jan 1970 18:27:20 GMT