The national flag of Turkey, officially the Turkish flag, is a red flag featuring a white crescent and star on its emblem, based on the 18th-century Ottoman Empire flag. The flag is often called "the red flag", and is referred to as "the red banner" in the Turkish national anthem. The measures, geometric proportions, and exact tone of red of the flag of Turkey were legally standardized with the Turkish Flag Law on 29 May 1936.