"Sun, 18 Jan 1970 18:15:44"
Convert date and time to unixtime.
Another datetime format string at UTC
YYYYMMDD
19700118
Only TIME
18:15:44
General datetime
1970-01-18 18:15:44Z
For Database
1970-01-18 18:15:44
For HTTP1.1
Sun, 18 Jan 1970 18:15:44 GMT