The value of the single bitcoin is established, as for the classic market, by buyers and sellers: it can therefore be said that the value is given by the encounter between demand and supply. No state or bank can establish or guarantee its value.
Think of auctions: millions of them are played every day in the world.
The most disparate categories of objects can be sold in these auctions, but they are typically scarce goods.
Well, how do you establish the price of one of these objects?
It can be estimated and provided with auction bases, but the true value will be established by offers made by the public.
For the bitcoin asset, things work in a similar way.
The places appointed to carry out these auctions are typically online exchanges but they can also be physical spaces where sellers and buyers meet. Those who sell bitcoins typically offer a price trying to achieve the highest possible profit, or sell at a price higher than that paid at the time of purchase, while buyer proposes an offer trying to get the most advantageous price.
When demand and supply meet, the instant bitcoin price is born.
There are places where these instant prices are collected and the average bitcoin price is obtained. The best known is CoinMarketCap, a site that collects the price of bitcoin and many other cryptocurrencies, but also marketcaps, daily volumes, circulating supply and other useful information.
Remember that, as a general rule, if the volumes are reduced, as well as the places assigned to the exchange, the price changes will be greater.
Volatility tends to decrease when volumes increase.
For this reason the value of the single bitcoin can undergo very important variations and for the moment the asset is considered high risk.
To better understand the concept of volatility and how it can be used to our advantage, I invite you to read the chapter Why should I convert my savings into something so volatile?
