Bitcoin transactions are one of the most secure transfers of money that can happen today. There are a few things that every bitcoin transaction consists of. This would be the header and the input and the output.
The input of a bitcoin transaction is showing that the prior balance of the wallet contains a certain number of bitcoins available to use. These bitcoins are then transferred forward to the current transaction that is about to take place.
The header of a transaction explains what the purchase is for and can be set by the buyer before the time of currency exchange. This header is also encrypted with a hashing function to increase the anonymity of the transaction. This is just one of the features that keep bitcoin transactions so secure on the network. If at any point, one of the miners feels as if the transaction should not be completed or is fraudulent, it can be flagged and rejected.
The output of the transaction is how much and where the amount of bitcoin is supposed to be headed. The user giving the bitcoin determines how much and to where the bitcoins are headed based on the public key provided by the seller. All of this information is included in the hash of the transaction, which is what gives this transaction a specific hash address that can be found in the blockchain. When a bitcoin transaction takes place, the bitcoin amount can be selected to be exchanged.
These are the three main portions of a bitcoin transaction. Therefore it is believed to still be one of the most secure forms of currency exchange. No matter where you are at in the world, the rate of exchange is 1:1 meaning there is no loss or gain of money no matter where you sell/buy a bitcoin.