Transactions can be made instantly, yes. Like a credit card, when you make a Bitcoin transaction, you send it to the entire Bitcoin network. Thus, in a few seconds, every other Bitcoin customer will receive it. However, the fact that other clients receive the message does not guarantee that the transaction is permanent. Since there are many transactions going on in Bitcoin Blockchain, the number of transactions pending verification is high. Minors will need to include the transaction in the next block. The blocks constitute the blockchain and a new block is added every 10 minutes (this is the theoretical average time, the actual average being 8 to 9 minutes). Whenever your transaction is included in a block, you can be almost certain that it will be permanent, but it is still possible that the block is orphaned. After an extra block has been added to the block with your transaction, the odds of being orphaned are negligible. Originally, the Bitcoin community had suggested that six blocks or confirmations be the perfect time to consider a transaction as irreversible. It takes an average of one hour to get the 6 confirmations, which makes this settlement network far superior to any existing system. Most valid transactions, certainly those with transaction fees, will be included in a block without any problem. In addition, millions of transactions can be made, permanently, on the Lightning network, a second layer above Bitcoin, benefiting from the security of the main channel.