A bitcoin transaction is just a bunch of data that describes the movement of bitcoins.
||4 bytes||Which version of transaction data structure we're using.|
||Variable||Indicates the upcoming number of inputs.|
||Variable||Indicate the upcoming number of outputs.||Output(s)||
||4 bytes||Set a minimum block height or Unix time that this transaction can be included in.|
- All of the data in a transaction is in hexadecimal.
- The following icon indicates that the data is in reverse byte order: ⟲
In further detail; the transaction data tells you how to unlock existing packages of bitcoins (from previous transactions), and how to lock them up again in to new packages.
A raw transaction is sometimes called a "serialized transaction", because it's just a bunch of individual pieces of data zipped up in to one string of data.