Heat the oil in a large pot or stovetop popcorn popper over medium heat until it's shimmering but not smoking.
Add the popcorn kernels to the pot or popper, ensuring they form an even layer on the bottom.
Cover the pot with a lid or the lid of the popper, and if using a pot, hold the lid slightly ajar to allow steam to escape. Shake the pot or popper gently to coat the kernels with oil and prevent them from burning.
Listen for the popping sound as the kernels heat up. Once the popping slows down to about 2-3 seconds between pops, remove the pot or popper from the heat.
Carefully remove the lid, keeping it away from your face to avoid steam burns. Transfer the popcorn to a large bowl and immediately sprinkle it with salt, tossing gently to coat evenly.
If desired, drizzle melted butter over the popcorn and toss again to coat.
Sprinkle any additional seasonings such as nutritional yeast, chili powder, garlic powder, or Parmesan cheese over the popcorn and toss gently to distribute.
Serve the freshly popped popcorn immediately while it's still warm and crispy. Enjoy as a snack or as part of a movie night or gathering.
Store any leftovers in an airtight container once cooled. Popcorn is best enjoyed fresh but can be stored for a day or two. Reheat in the oven for a few minutes to restore crispiness if desired.