A civil ensign is an ensign (maritime flag) used by civilian vessels to denote their nationality. It can be the same or different from the state ensign and the naval ensign (or war ensign). It is also known as the merchant ensign or merchant flag. Some countries have special civil ensigns for yachts, and even for specific yacht clubs, known as yacht ensigns.
Most countries have only one national flag and ensign for all purposes. In other countries, a distinction is made between the land flag and the civil, state and naval ensigns. The British ensigns, for example, differ from the flag used on land (the Union Flag) and have different versions of plain and defaced Red and Blue ensigns for civilian and state use, as well as the naval ensign (White Ensign) that can also be used by yachts of the Royal Yacht Squadron.