I think your mistaking them with ipods
MP3s became popular in the early 2000's.
iTunes is by far the most popular mp3 site, for music and videos. You can download free mp3s, and also purchase mp3s from iTunes. The website is http://www.itunes.com.
Very few mp3s players have a digital recorder. This is not a very popular option for mp3 players. One model that does is the Sony ICD BX800, which can be ordered on Amazon.com.
"MP3s" is the correct plural form of MP3.
No
yes mp3s can help people learn because it helps them concentrate
Internet
Phillips manufactures a boombox, the PSS110, which has the added convenience of playing MP3s.
Mp3s are fairly ubiquitous and can be purchased at any big box store such as Walmart or Target. They can also be found at large electronics and appliance chains such as Best Buy. For Apple mp3s (iPods), they can also be purchased at the Apple stores. One can also find mp3s online at Amazon and eBay.
Not directly onto the game, but if you have mp3s on your system you can play them by going to Easydrive --> Soundtrack --> Custom
Get yourself some audio editing software, and follow the directions.
As technology advances, cassette players are being replaced with CD players and more popularly iPods and mp3s. However, they soon will be valuable antiques.