Many argue that mp3's are of lesser quality than CDs. This is partially true. CDs are recorded at a sample rate of 44100 hz, and so are most mp3's.
Mp3's ripped, or encoded, from CD are ALWAYS of equal or lesser quality than the original music on the CD, because quality can never be improved over the original when copying anything. However, mp3's ripped from vinyl records, reel-to-reel tapes or uncompressed digital audio can certainly be of better quality than CD quality.
The reason why mp3 files are about a tenth of the size of the same music recorded to CD is that CDs use a 30 year old codec, whereas the mp3 codec is much more modern, thus allowing for better compression.
The problem with mp3 quality is that people are so uneducated. When the average joe gets an mp3 player and wants to encode his music collection, he does so at the default bitrate of the ripping program he is using. For example, foolish rippers such as the evil RealPlayer state that 64 kbps is CD quality. 256 kbps+ is the best to rip at for quality.
For some, but not all audio, it is wisest to use a variable bitrate (VBR). This encodes at a higher bitrate for more musical data, and a lesser bitrate for less data. For example, a VBR encoding of a song may have a lesser bitrate for the introduction where only one instrument is playing, than for the more intricate passages where more detailed sound is being made.
iTunes is the best mp3 ripper I have ever used, unless you want to use LAME from the *NIX command line.
Mp3 audio can be played on a variety of devices, including but certainly not limited to: Personal computers, most modern DVD players, portable mp3 players, such as Apple's iPod, or any inferior knock-off devices made by other companies.
In the mid-1990s, members of the GNU project created sets of software tools that allowed CD audio to be 'ripped' to a digital storage device, such as a harddrive. With the aid of software such as Winamp, iTunes or XMMS, this music could be played back at almost-CD-quality. Optionally, this ripped audio could be shared to others by floppy disk, or over networks, such as the internet.
Then Napster happened, and the average joe could get involved. Napster ended in a messy legal battle, involving Metallica, and the RIAA.
Napster's flaw was the fact that it had a central server, which could be shut down. The newer, more robust networks that rose to take napster's place do not have this problem, instead relying on 'ultrapeers'. See Kazaa, Morpheus, Gnutella, Overnet, eDonkey...
Some, such as the iTunes music store, have decided to sell music files. THESE ARE NOT MP3's. the iTunes music store sells m4p files, the DRM-crippled equivalent of m4a's. The codec for these files is the AAC codec, used for new high fidelity DVD audio. The Sony connect service sells DRM-crippled ATRAC3 encoded files, known for their lack of quality.
See also LAME, napster, p2p, ogg (AKA vorbis), AAC, m4a, wav, CD, RIAA.
I want an iPod, because it is a great mp3 player.
Why buy CDs when you can share mp3's?
2) "mp3" is what dumbasses call any MP3 (Player) that is not an iPod.
Sandeep: 1) its MP3 Player,
2) iPod IS an MP3 Player
3) ur a f*cking dumbass
Sandeep: yo, i ripped all my CDs to 192kbps MP3s
mp3 has become synonymous with music piracy, though that isn't neccessarily so. even p2p file sharers like kazaa are completely legal...it's only some of the content that isn't
me: stfu shitcock