These days, almost everyone has a MP3 player of some kind. Some are integrated into phones while others are even made into the handles of sunglasses. It makes listening to music easy and accessible wherever you are.
Most noticeably, virtually every mobile phone has an integrated MP3/MP4 player of some kind. Mobile phones have come down in price over the years and with mobile providers not locking you down to lengthy contracts, it makes them more affordable for everyone. For example, O2 Simplicity
means you can stick with your current phone and pick a SIM only simplicity tariff, which gives our best value. You can then get data addons to your plan which then gives your mobile phone access to the internet.
Virtually all mobile phones have an integrated MP3/MP4 player which means you don't have to carry an additional device with you makes it very convenient. Take for example, the Samsung Galaxy Ace Purple from O2
which not only runs the Android Operating System with access to Android Marketplace (so you can download and install your own Apps for your phone) but also has a built in MP4/H.264/H.263 player as well has a MP3/WAV/eAAC+ player. This means you can have your mobile phone with you while still having an MP3/MP4 player to listen to music or watch videos on. The 3.5" screen is a good decent size for watching videos as well compared with the smaller screen size on the older MP3/MP4 players.
Phones with integrated MP3/MP4 players are becoming more and more convenient and an option for people than the traditional standalone MP3/MP4 player. They provide more functionality and features as well as the added convenience of only having to carry one, 'all-in-one' device rather than two or three devices.