Welcome to the crypto space! Yes, all transactions are stored on the blockchain and it's not a 'code' per se. Bitcoin is best described as a virtual currency. There are no physical cash forms, coins, or tokens, they exist electronically based on an open-source software released by an unknown developer under the pseudonym Satoshi Nakamoto.

The Bitcoin network is decentralized in that no central authority controls the amount of bitcoin in circulation. Bitcoin doesn’t need a banking system or government for bitcoin tokens to be created, exchanged, or stored, and is not involved in traditional exchange rates. Instead, Bitcoin leverages a peer-to-peer network commonly referred to as the ‘blockchain.’ The blockchain technology used in Nakamoto’s software is the key to Bitcoin’s defining characteristics.

We expand on this in our BTC 101 guide, feel free to check it out, it's a great place to start for beginners! http://bit.ly/Bitcoin101Guide

Cheers!