Most common formats are proprietary, but MPEG audio and similar schemes may eventually supplant these proprietary formats. The most common streamed audio format is Realaudio from Progressive Networks . This technology works over limited bandwidth and is affordable for educational and broadcasting institutions. Other less common ones are .aiff, .voc, mp2. In order to play sound on any computer, it must come equipped with a sound card.
Many computers come with sound cards built in.
However, if you need one, there are many affordable ones available. There are many excellent free and shareware sound utilities available. Most sound cards are built for recording and playing sound. Most also come with the ability to sample from a CD player. Once you have a sound sampled, you can use an editing application to shape the sound according to your needs.