The basic bitcoin transaction has one input and two outputs. If you browse a block explorer you will see this is the majority of transactions on the network.

In a transaction the input is the total unspent bitcoin in a public address that was transferred to that public address from the previous transaction. The first of the two outputs is the public address where bitcoin is sent to and the second output is the senders public address, known as a “change address”.

As you can see on the left column there is one input address (from the previous transaction) and on the right column there are the two outputs. The first output is the bitcoin that person A sent to person B and the second output is a “change address” which belongs to Person A, the sender. Example: Person A has 2 bitcoin in his public address and he sends .5 bitcoin to person B. The 1st output address belongs to person B which now has .5 bitcoin. The second output is the “change address” which belongs to person A which gets 1.5 bitcoin back in a new address, minus any fees that was paid to miners to include the transaction in the block.

Here is a good example of the first three transactions within this particular block. Note that the transaction at the top doesn’t have an input because this is the “coinbase” or the first transaction awarding the mining pool the 12.5 bitcoin reward (plus transaction fees) for correctly guessing the random hash or number.