You'll almost certainly have seen the term 'IEM' appear sporadically across the pages – virtual or in-print – of What Hi-Fi? It's a term with which many are surely familiar, although the number of people who could point to exactly what the term stands for, let alone what it means in practical terms, maybe a little lower than you'd think.
If you're au fait with all there is to know about IEMs, feel free to pat yourself on the back. If you're still a little confused about what they are specifically, how they differ from 'standard' in-ear headphones/earbuds, not to mention the benefits and drawbacks that they bring, we have all the answers you'll ever need.
