Okay, let's make some TNT. For this recipe, you are going to need four sand and five gunpowder. Place your sand like so and your gunpowder like so. That's your recipe for TNT. Let's pull that block down and go blow some stuff up.
You place TNT by right-clicking with it and set it off by either punching it or triggering it with Redstone. I'm just going to punch this and run away. And there it is. So all these blocks were broken but not entirely destroyed. So TNT is a quick but messy way to mine.
Something fun to do with TNT is make landmines. Dig down one block. For this, you'll need TNT. I've got some cake here to act as my bait and a pressure plate. I'll use a sign as well. Place my TNT in that one block, there. Place some dirt on top of it to hide that TNT. Actually, let's get rid of this block right here and let's bait this trap with some cake. Place a sign, a nice enticing sign, and then put your pressure plates one block next to your TNT. This will act as an input and set your TNT off. So if someone comes along, wants some cake and wonders what that sound is . . . spooked you!
So here I found this natural sand bridge. All this sand is just floating in the air. Normally sand can't float, gravity will pull it to the ground but this has occurred naturally. Now if I was to force these blocks to update, they will all fall to the ground. Now I'm going to do that with some TNT. I'm going to place the TNT one block below the sand and one block over. If I place the TNT directly below it, that could force the sand to update and fall. And I'll place a Redstone path. Not too far, but a good distance so I'll have a nice view. Okay, here we go. I'll hit this lever, the current will travel down this Redstone path and activate the TNT. Here we go. Oh yes! Okay, that felt pretty good.
Alright, so to wrap up, a little PSA about TNT. It's all fun and games until this happens. So now you think, "Great, you have to live with this TNT in your house or destroy your house." But that's not true. You can actually use a bucket of water to completely incapacitate this TNT. With that bucket of water, right-click on top of the TNT and cover it in water. Now, when you set this off, it won't damage any items but it will hurt you so let's get out of here. Hit it to activate it and run away. And there you go. TNT is gone, pick up the water and your house is totally safe. So have fun, be safe.