"How do you want your steak?" is a question with more wrong answers than right ones, because most people are guessing. Here's what each doneness level actually means, what it looks like inside, and how to hit it on purpose instead of by luck.
A quick note before the ladder: these levels apply to whole cuts of beef (and lamb), where the inside was never the food-safety risk, so the centre is a matter of taste. This is not the same as ground meat or poultry, which is covered in safe temperatures vs doneness.
The Doneness Ladder
Rare
A cool to warm red centre, soft to the touch, very juicy. The outside is seared, the inside barely warmed. Sits at the bottom of the temperature ladder.
Medium-Rare
A warm red centre fading to pink at the edges, still very juicy but a touch firmer than rare. This is the level many cooks and steak lovers consider the sweet spot for tender cuts, because it balances juiciness with a warmed-through centre.
Medium
A warm pink centre, firmer again, still juicy but less so than medium-rare. A popular middle-ground choice.
Medium-Well
Only a hint of pink at the very centre, noticeably firmer, and drier as more moisture has been driven off.
Well Done
No pink, cooked through, firm throughout. The driest level, sitting at the top of the ladder. Cooking a steak this far asks a lot of a lean cut, so a fattier cut copes better if this is your preference.
The Touch Test (and Why the Thermometer Wins)
You may have heard of judging doneness by pressing the steak and comparing the firmness to parts of your hand. It's a useful rough feel that experienced cooks develop, but it's imprecise and varies with the cut and thickness. For repeatable results, a thermometer beats the touch test every time. Use touch as a backup, not your primary guide.
A Word on Thickness
A thick steak and a thin steak at the same doneness are cooked very differently. A thin steak races through the doneness levels in seconds, so it's easy to overshoot; a thick steak gives you more margin and benefits from a sear-then-finish approach. Thicker cuts are far more forgiving if you're learning to hit a target.
The Bottom Line
Doneness is a ladder of internal temperatures, from a cool red rare centre up to a cooked-through well done. Pick your level, measure with a thermometer, pull a touch early for carryover, and you'll serve exactly the steak you meant to, every time.