These music resources have been created as a response to expanding technology and needs of customers who wanted easy, quick access to music. They are almost always compressed using a lossy codec (usually MPEG-1 Layer 3, Windows Media, or AAC), which reduces file size and bandwidth requirements. Paid downloads are sometimes encoded with digital rights management that restricts copying the music or playing purchased songs on certain digital audio players. Main articles: Digital music store and Comparison of digital music stores
