trading in Bitcoin was predominantly in US dollars, it has now moved to being predominantly in Chinese Yuan. This highlights Bitcoin’s nature as both a highly speculative investment and as a tool for evading currency controls[^10].

![Top: Price fluctuation of Bitcoin over time. Bottom: Traded volumes by exchange (left) and by currency (right).[]{data-label="fig:volumebyexchangecurrency"}](figures/price_exchange.pdf "fig:"){width="90.00000%"} ![Top: Price fluctuation of Bitcoin over time. Bottom: Traded volumes by exchange (left) and by currency (right).[]{data-label="fig:volumebyexchangecurrency"}](figures/volume_exchange.pdf "fig:"){width="45.00000%"} ![Top: Price fluctuation of Bitcoin over time. Bottom: Traded volumes by exchange (left) and by currency (right).[]{data-label="fig:volumebyexchangecurrency"}](figures/volume_currency.pdf "fig:"){width="45.00000%"}

![Difficulty[]{data-label="fig:difficultyblocksize"}](figures/difficulty.pdf "fig:"){width="45.00000%"} ![Difficulty[]{data-label="fig:difficultyblocksize"}](figures/blocksize.pdf "fig:"){width="45.00000%"}

The Bitcoin network relies on ‘miners’, or members that contribute computational power to solve a complex cryptographic problem and verify the transactions that have occurred over a short period of time (10 minutes). These transactions are then published as a block, and the miner who had first published the proof receives a reward (currently 25 bitcoins). The maximum block size is 1 MB, which corresponds to approximately 7 transactions per second. In order to ensure that blocks are published approximately every 10 minutes, the network automatically adjusts the difficulty of the cryptographic problem to be solved.

Bitcoin mining requires specialised equipment, as well as substantial electricity 