How to Add Album Art to an MP3 The way we listen to music has fundamentally changed since we moved away from physical CDs and toward digital formats like MP3s. One thing, though, appears to have remained the same. We still categorize our music by albums, which always featured an...

Trade by barter is the direct exchange of goods for goods, goods for services, or services for services. It was a system of exchange which was in use before the introduction of money.