If you're trying to buy, list, create or bid on an NFT, you might see your transactions fail or revert. This usually happens because of one of a few different reasons:
The transaction "ran out of gas"
You pay a "gas fee" to the network on any transaction you make on a blockchain. These gas fees exist to regulate demand for transactions. The more people send transactions to the blockchain, the higher gas fees get. Gas fees are basically the price for having the network validate your transaction. But because the capacity of the network (also called blockspace) is finite, not all transactions can be validated, which means there's always a minimum of gas needed to validate transactions at any point in time.
If you sent a transaction right before that minimum spiked, it's possible that your transaction did not have enough gas to be processed. You can either manually increase the gas on your transaction or try again when gas fees are lower.
You tried to buy an inactive listing
Whilst we do our best to aggregate and show the current status of all listings, it's possible that someone tried to purchase that listing at the same time as you and had their transaction confirmed before you sent your transaction. This would make the listing inactive and means that it was impossible to buy the NFT.
The smart contract rejected your transaction
There are various reasons why a smart contract might reject a transaction when it violates the functions of the smart contract. That's possible if you tried to send a transaction using tokens the contract doesn't support or using more tokens than you have.
Some NFT collections also have special rules in their smart contract. If a collection has a rule that only allows each wallet to own one item from its collection, a transaction to buy a second one would fail.