Boxer shorts are a loose fitting under garment worn by boys and men. They have been popular in the UK for many decades, particularly with teenage boys and young men. Most boxer shorts are designed with a "fly" at the front, so that they do not have to be removed when going to the toilet. The fly is usually closed up with buttons, or sometimes a zip, but increasingly, boxers have an "open fly" design whereby there is a flap of structured fabric which covers the hole but can be moved out of the way when needed.
Boxer shorts are usually quite baggy and even in tight fitting boxers; there is a lot of excess fabric in the crotch area. This is to allow for flexibility and movement, in particular when sitting down or bending forward. This is particularly important in growing boys and teenagers.
One reason why boxer shorts have become so popular with boys is that they come in such a wide variety of colors, styles and prints. With regular boy's briefs, the design element was limited due to there being such a small area of fabric, and little range of types of material used to make them. However, boxer shorts are more like shorts and thus, they come in all different fabrics and have a much greater surface area to allow for designs and prints. The majority of boxer shorts available are plain, in neutral colors such as black, navy, grey or white. However, there are also boxer shorts in bright colors and in various patterns. One of the most popular styles of boxers is loose, thin cotton in a plaid pattern or with vertical stripes. There are also thousands of pairs of "novelty" boxer shorts out there - from "The Simpsons" designs to Mickey Mouse designs, there is something to suit everyone and this variation is something which really appeals to teenage boys in particular.
There is also some scientific evidence which suggests that boxer shorts are actually better than tight briefs because they are cooler and allow for more movement. It has been shown that tight underwear and hot temperatures are bad for sperm production. Therefore, loose boxer shorts which allow more cool air in to the genital area, and do not compress the area in any way, may be positive for sperm production and help to ensure that everything can function as normal. This is very important for growing teenage boys and anything which promotes healthy, normal growth is a positive thing.
There are clearly many reasons why teenage boys may choose to wear boxer shorts instead of tight briefs. Boys boxers are practical, comfortable and fashionable and for those who like the idea of boxers but would like a little more support, they also come in more elasticized fabrics, in a tighter fit (often known as boxer briefs) which allows the wearer to have the best of both worlds. Most teenage boys will go through various phases of preference for their underwear and will eventually settle on the style which they deem to be the most comfortable and the most fashionable for them.