In the UK, the term dress shirt is reserved for a particular type of formal shirt. There are formal day shirts for wearing with morning dress, and the white dress shirts used as eveningwear.
A day dress shirt is fairly similar to a normal shirt, and is usually white, with a stiff detachable collar, though other designs, such as a fine horizontal blue stripe, are also appropriate. Double cuffs are most common. This sort of shirt is also required to be worn by some barristers and judges.
An evening shirt, for wear with eveningwear, for example as part of black or white tie has some unique features. In the U.S., this shirt is often called a tuxedo shirt or tux. shirt. The shirt is always white.
The shirt required for white tie is very specific. It should have a detachable wing collar and be fastened with shirt studs instead of buttons on the front. The studs are normally mother of pearl set in gold or silver, but black onyx inlay is also permissible. The cufflinks should match the studs. The shirt front has panels made of different material from the rest of the shirt which are the only parts seen under the waistcoat. The shape of the panels, one on each side, is either rectangular, or the older U-shape (designed to sit under the older 1920s U-shaped waistcoats, now largely replaced by the more modern V-shape). The material for the panels is either layers of thick plain cotton that is heavily starched (this type is often called a boiled front shirt as the shirt needs to be put in boiling water to remove the starch before cleaning), or marcella (piqué) cotton. Marcella is more common, but a little less formal, though still appropriate, since it was originally designed to be used on formal evening shirts, as the ribbing can pick up more starch and create an even stiffer front. Traditionally, collarless shirts with a detachable wing collar fastened on with collar studs have been used, but all-in-one designs are occasionally seen, though this is considered incorrect and to give a poor appearance by many. Cuffs are single, and heavily starched (if the front is marcella, the cuffs usually match).
Black tie offers more leeway. Shirts may be soft (not starched), which gives the options of unstarched marcella or a pleated front, as well as the white tie shirts, which may also be worn with black tie. The collar is still sometimes a stiff high wing collar (common in America, though the attached variety is more popular there), or a turndown collar (more frequently seen in Britain). In past decades, particularly the 1970s, ruffled shirt fronts were made fashionable by Will Hunter, although they are now out of favour. Dress-studs are optional, and are onyx set in either silver or gold if used; otherwise the buttons are normally concealed under a placket. Cufflinks tend to be as simple and understated as possible, and harmonise with, if not match, the studs.