UTC+03:00 is an identifier for a time offset from UTC of +03:00. In areas using this time offset, the time is three hours later than the Coordinated Universal Time.
Following the ISO 8601 standard, a time with this offset would be written as, for example, 2019-02-08T23:36:06+03:00.

As standard time (all year round)

Principal cities: Moscow, Istanbul, Riyadh, Baghdad, Nairobi, Addis Ababa


Most of European Russia, including Moscow, St. Petersburg, Rostov-on-Don, Novaya Zemlya, Franz Josef Land. From October 26, 2014 Moscow and most other parts of European Russia started using UTC+03:00 again, all year around. Also on September 7, 2016, Turkey started using UTC+03:00 all year round.
Besides the names mentioned above, the name 'Eastern Europe Forward Time' is sometimes used.

Arabia Standard Time

Arabia Standard Time, or AST, is used by some countries in the Middle East. As this time zone is predominantly in the equatorial region, there is no significant change in day length throughout the year, so daylight saving time is not observed. Between 1982 and 2007, Iraq observed Arabia Daylight Time but the government abolished DST in March 2008.
Arabia Standard Time is used by the following countries:

Caucasus region

''Principal cities: Kiev, Bucharest, Athens, Jerusalem, Sofia