earbuds (or earphones) are a typical go to for most people out and about. The are the things that most devices you buy ship with - very common.
They often have inline controls with a mic for phone use. earbuds are also great in offices, or environments where you want to listen to music but still be aware of your surrounds. Like open back headphones they often let a little ambient noise in compared to IEMs. If you need to quickly talk to someone they are easy to take out and put in your ear without a lot of fuss.
Earbuds are a good choice for everyday, casual listening. You'll lose some audio quality but for most people that is not a problem.