As the number of states allowing their residents to obtain Concealed Weapons Permits has increased, so has the number of guns being bought specificaly for carrying. This enviornemnt has proven to be the perfect catalyst to encourage gun companys to produce new and better pocket pistols that are lightweight, comfortable, easy to operate, and reliable.
These guns differ from sub-compacts in that they are very rarely built on a the platform of a full-size service pistol. You can scale down a large gun only so much before your reach the a point of diminishing returns where function is concerned. Pocket pistols are usually built on on their own platform around a very small cartridge. The .380 or .32 are customary with the 9mm usually being on the large end of the spectrum with these guns where cartridge size is concerned.
Most pocket pistols are usually very lightweight and easy to conceal. Women love them because they work with carry options that do not require adopting a complete change of dress as is usually required when starting to a carry a larger gun. Slide operation on many of these little pistols is often easier to manipulate as well with some designs, such as the Beretta Tomcat, incorporating a tilt-up barrel which allows the pistol to be loaded without touching the slide at all.Reduced recoil is another benefit that comes along for the ride in most small gun designs. Such a benefit is often looked at as a disadvantage however as it is indicitive of lower pressure shots and lower overall velocity of the fired round once it leaves the barrel. Slower speeds translate into lower power on the performance scale which has many self defense experts making the claim that pocket pistols are not a good choice for concealed carry if you actually think you may need to use the gun at some point to stop a violent assailant.
The truth is that any gun carried is better than the one left at home. Those who carry pocket pistols usually known themselves well enough to admit that they'll carry the small gun consistently while they'll leave their high-performance 1911 at home more often than not if that was the only choice available to them. If this is you, it is highly advisable to purcahse the pistol that will actually go with you at all times and let the pros follow their own advice in their selection of guns.
Pocket pistols work well for IWB holster carry, pocket carry, and ankle carry. Some work well with shoulder holsters as well. However you choose to carry one of these guns the slight burden will be ofset by the level of comfort you receive knowing that it's with you.