When you pay for bread, the baker does not accept money to eat it. They accept it because it can pay for flour, rent or someone else’s work. That role is called Medium of Exchange. Bitcoin raises the same practical question: can you actually use it to pay in this situation? The answer depends on the recipient, payment method and costs, not merely on the asset having a market price.
Imagine a grower who has grain but needs tools. The toolmaker does not want grain. Direct barter stalls: each person must want what the other offers at the same time. Instead, the grower can sell grain for an accepted medium and then buy tools with it. The Bank of England, the UK’s central bank, uses this principle to explain how money eases trade. This is an illustration of money’s function, not a claim that money historically emerged this way everywhere. Nor does it mean barter disappears or every seller agrees to accept the same medium. [1]
At the checkout, theory becomes a practical question. Does the shop accept Bitcoin now, using a method your wallet supports? Bitcoin.org notes the limits of acceptance. A sticker or an old map listing does not establish present availability. Agree on the method and amount before sending. Merchant Adoption means shops introducing these payments; functioning purchases are a useful way to assess it. Paying for lunch demonstrates that particular use, not that you can pay for anything, anywhere, in the same way. [2]
Imagine a purchase priced at 200 CZK, Czech crowns. The buyer sends bitcoin (BTC), but a payment service converts it and pays the merchant crowns. Bitcoin.org describes processors that offer this service. Bitcoin genuinely participates in the payment, but this does not establish bitcoin pricing or continued BTC ownership by the merchant. The crown still sets the price. That is the Unit of Account: the unit in which a price is expressed. The quoted exchange rate, fees and quote expiry therefore matter before payment. [2]
Take a simple model: a purchase costs 100 units, with an extra fee of 1 unit. The fee is 1 % of the price. For a purchase costing 10 units, the same fee is 10 %. Total spending is 101 and 11; those totals are not the denominator — the goods’ prices are. Bitcoin.org explains that an on-chain payment, recorded directly in Bitcoin’s chain, does not have a fee set as a simple percentage of the amount sent. Include any conversion and service costs when comparing options. These figures illustrate the difference; they are not current prices. [2]
The buyer’s phone says the payment was sent. The merchant still needs to verify it on their own side; a screenshot alone is insufficient. Bitcoin Developer Guide distinguishes a transaction broadcast to the network from one included in a block, the next batch of transactions added to the chain. Inclusion gives it its first confirmation. Each additional block increases the work needed to rewrite that history. A double spend attempts to use the same coins for another payment. More confirmations therefore mean stronger protection against that attempt, not absolute certainty. A small purchase and the sale of expensive machinery need not follow the same acceptance procedure. Waiting should reflect the amount and risk, not a universal promise. [3]
Lightning Network carries payments through a network of payment channels without recording each purchase in a block. Along the route, the necessary amount must be transferable in the required direction. BOLT 4, the routing specification, distinguishes temporary_channel_failure, a temporary channel obstacle; amount_below_minimum, an amount too small; and fee_insufficient, an inadequate routing fee. You need not memorise these names: they explain why a payment sometimes fails. Lightning support in an app does not guarantee success or zero costs. What matters is the actual outcome for the recipient. [4]
Calling something money does not by itself determine what a merchant must accept. Bank of England explains the British term legal tender: it has a narrow meaning when offering full repayment of a debt if the contract does not specify another payment method. It is not a general order for every shop to accept any cash. This is a British example, not a rule for all countries. Separate local legal rules from the agreement with the recipient and the technical ability to transfer funds. Each addresses a different part of the situation. [5]
The European Central Bank (ECB) describes a unit for prices and a way to preserve value alongside the medium of exchange. Store of Value means carrying purchasing power into the future. These functions can overlap, but one does not establish the others: you can use BTC to pay for a purchase priced in crowns even while bitcoin’s exchange rate fluctuates sharply. Distinguishing the functions does not prescribe mandatory development stages or a certain order Bitcoin must follow. To understand its actual use, examine completed purchases, contractual pricing units and the value of savings over time separately. [6]
For the clearest picture, read this entry together with Unit of Account, Store of Value, Merchant Adoption, Lightning Network. The reverse links also lead from Sound money, Bitcoin Pizza Day, Regression Theorem, Commodity Money.