What’s the one ingredient you always keep stocked, and why?

I’m trying to get more into cooking, but I always feel overwhelmed by recipes with a million ingredients. I’ve decided to take a simpler approach and focus on keeping a few key things stocked in my kitchen that I can use in lots of meals.

So, if you had to pick ONE ingredient you always have at home (besides salt and pepper!), what would it be and why? Something versatile or that makes every dish better would be awesome to know about!

Bonus points if you share how you like to use it