Is it time zone or +1 hour to local time


I was looking to this entry on many server & finding there is +0100, +0500 at the ending of time, so question is, it is time zone or some offset setting.

See the example below -

Bigfix Agent Registration Time - Sat, 01 Aug 2015 12:31:51 +0100

It is current offset to Universal Time UTC
It will shift as your endpoints pass into and out of daylight savings time

Example, EST -0500. And during DST. EDT -0400