A garden fire pit is focal point for family gatherings in late spring and early autumn as well as summer evenings. A fire pit is a way of having a campfire while containing the mess.
You can install a firepit on your patio as a permanent feature or you can have it sitting above ground.
If you buy a firepit they are mostly stainless steel shallow bowls with feet that sit about a foot above ground level. For maximum safety you need to dig a hole to put them into, so they sit slightly below ground level and present no trip hazard.
If you install a fire pit on your patio you can take out one slab, dig a hole, put half bricks in the corners of your hole so you can put the slab back again when you are not using the firepit. Dig the hole deep enough that you can leave the firepit inside, even with the concrete slab on top.
A fire pit is different from a barbecue because is is meant to give flames for light and heat. A barbecue never gives visible flames except when you are lighting it. If you want to cook on your new firepit you will need to buy an optional grill attachment.
You can build a fire pit yourself, just remember to allow for air to get to the base, or the wood will not burn well