The sound card or audio card is the expansion card used to improve the sound of the computer, to manage sound applications and to connect external sound devices to it. Although most computers have some sound capabilities they do not usually have enough to run complex audio applications and it is necessary the connection of a sound card.
Some motherboards have a built-in sound card so it is not necessary to plug a new sound card to the computer but although it is built into the main board they are still considered sound cards. Sound cards have a lot of different ways to connect to the PC via different ports like PCMCIA, PCE-E, IBM PC Parallel Port, IEEE 1394, ISA and most commonly PCI and in the latest times some by USB but those are considered USD devices more than cards.
Historically, games and apps in the computer just used the built in speaker of the computer and Sierra On-Line was the first developer in using the capabilities of sound cards, this increased the sound capabilities of games to an extent never known before and soon it became a standard to use them, but the most known Sound Cards in history have been Sound Blaster and all the compatibles.
The technological advances in the audio field have been also featured in Sound Cards. They started to be mono, and in the early 90’s the stereo sound cards hit the market, allowing the chance of plugging external stereo speakers to the computer, in the late 90’s the 5.1 channel audio arrived to the computer world and the latest soundcards are able to support up to 8 audio channels with the 7.1 speakers.
Although the 7.1 sound cards are the latest hit in the market the most used soundcards nowadays are the built-in sound cards. They are typically stereo with the microphone input, but as they are built into the main board there is no need to spend extra money in a new sound card and the most part of people do not use 5.1 or 7.1 features in the computer, they just use a pair of speakers and it is enough with a built in sound card to do so. Some main boards have a 5.1 or 7.1 sound card, but they are the less. However, there are a wide range of professional sound cards with much better capabilities for those who need them.
In the past it was necessary to configure the Sound Card for each game or sound application but since the development of the PnP technology and the new drivers, it is much easier to do so and in the most part of apps the user doesn’t need to input the kind of sound card used or any other parameters as they are provided directly from the driver. It was quite a pain to the user to have to configure the IRQs and the DMA channels, but this is no longer used right now and everything is done automatically.