Almost every smart phone on the market comes with an application that can play MP3s. Since most phones have a substantial amount of internal memory, storing MP3s on the phone is a great way for taking music on the go. In fact, there some online radio stations which actually allow downloading of content. That means that if you don’t have Internet access you can still listen to music which was streamed through your phone while you were at home. Also, storing MP3s on the phone allows you to maintain your music collection and have instant access to any song of your choosing just by inputting the title or artist. Most play applications are fairly sophisticated and not only allow you to search for a particular artist was song but also allow you to create playlists.
Also, if you don’t like the default play application on your phone, you can install another player by downloading an app from the App Store or from Google play. They are quite a few apps available so you have quite a few choices. I would recommend to maintain some sort of hierarchy when storing MP3s on the phone. That will simplify choosing for a particular genre or artist. Smart phones allow creation of folders and subfolders. So I would put MP3s from different artist or from different genres into their own subfolder. Also, you might want to organize MP3s by date.
While listening on a smart phone is usually done by using headphones or earbuds which were shipped with the phone, it makes a lot of sense to instead use loudspeakers because the sound quality will be so much better. Note, however, that you cannot connect regular passive loudspeakers to a cell phone. That would simply overload the phone. You will need to either an amplifier which connects to the phone or instead you can purchase some active speakers. Active speakers can connect directly to a phone.
Another way to play music over speakers is by using wireless loudspeakers. In particular Bluetooth speakers are often used with cell phones because the music can be streamed from the phone directly by using the built-in Bluetooth functionality. There isn’t anything required in terms of the transmitter. When creating playlists, you can easily stream your audio wirelessly. All you have to do is activate Bluetooth and set the phone to connect to the speakers. Once the connection is established, all music will automatically be streamed to the speakers. However, make sure that you pick some speakers that will still allow you to take a phone call on the phone directly. You surely don’t want the ring signal to be transferred to the speakers.