There's an idea that measuring your inseam is a bit, well, intimate. If you've seen that episode of "Friends" where Chandler visits Joey's professional tailor to be measured for a suit, you know that taking this measurement does involve putting one end of the tape measure in a delicate region: the crotch. We're talking about the crotch of your pants.
But during the pandemic, a lot of people shifted from buying clothes in stores, where they could try them on, to buying clothes online. And it turns out that the inseam of one's pants, even if they're comfy joggers, matters.
First, let's talk about what the inseam is. As you may guess from the word, it's the inside seam of the leg of your pants. It's the length from the crotch to the bottom hem, but it does not include the part of your pants from the crotch to the waistband; that is called the rise. The corresponding measurement on your body is from your physical crotch to the floor. You want to measure both your pants' inseams and your inseam (more on why in a minute).
The easiest way to get an accurate inseam measurement on pants is to lay your pants out flat. Put one end of a measuring tape at the crotch seam where the legs meet and run it down the pant leg to the bottom hem. That number is the inseam measurement for that pair of pants.