Yesterday, I had the opportunity to give a presentation on Bitcoin transactions, fees, and privacy for beginner and intermediate users. The experience left me with an interesting realization: many people have bought bitcoin, some even use it regularly, but very few truly understand what happens when they press the “Send” button.

See the presentation (SPA): Bitcoin Txs at Bitcoin Talks - Asuncion PY

That is not a criticism. It is perfectly normal.

That's me, walking around and talking about bitcoin txs at Bitcoin Talks

Most of us learned how money works through the traditional banking system. We open an app, look at a balance, and assume that money exists as a number stored inside an account. When we arrive at Bitcoin, we tend to bring that same mental model with us.

But Bitcoin is not a bank account.

And understanding that difference completely changes how we think about transaction fees, privacy, and financial sovereignty.

The Mistake of Thinking in BalancesThe Mistake of Thinking in Balances

When you look at a bank account, you see a balance. The bank keeps an internal ledger and simply increases or decreases a number whenever you make a transaction.

Bitcoin works differently. The network does not store balances. Instead, it stores pieces of bitcoin called UTXOs (Unspent Transaction Outputs), which are transaction outputs that have not yet been spent.

A simple analogy is physical cash.

Imagine you have three fifty-dollar bills. Your total wealth is $150, but there is no single object worth $150. There are three separate pieces of value.

When you buy something that costs $80, you do not cut a bill in half. You hand over complete bills and receive change.

Bitcoin works in a remarkably similar way.

Every time you make a transaction, existing UTXOs are consumed and new UTXOs are created—some for the recipient and usually one for yourself as change.

That means a Bitcoin transaction is not about “subtracting from a balance.” It is about destroying old pieces of value and creating new ones.

Where Transaction Fees Come FromWhere Transaction Fees Come From

Another assumption inherited from the banking world is that transaction costs depend on the amount of money being sent.

In Bitcoin, that is not how it works.

The network does not charge based on the amount of bitcoin you move.

It charges based on the amount of block space your transaction occupies.

A transaction moving 0.001 BTC can cost exactly the same as one moving 1 BTC if both consume the same amount of space.

What determines that space is primarily the number of inputs and outputs involved.

The more UTXOs you need to spend, the larger your transaction becomes, and the more fees you may need to pay to compete for inclusion in the next block.

To make this easier to understand, imagine you want to buy something worth $100, but the only money you have consists of two hundred 50-cent coins. You can certainly pay with them, but carrying and counting all those coins requires more effort. A single $100 bill would be far more efficient: it takes up less space in your wallet and is much easier to spend. Bitcoin works in a similar way. When your wallet accumulates many small UTXOs, future transactions become larger and more expensive because more pieces of data must be included. Consolidating those UTXOs is like exchanging a pocket full of coins for a single bill.

This is why users who receive many small payments often face higher costs later.

Their wallet accumulates dozens or even hundreds of tiny UTXOs that must eventually be spent as inputs. That is also why consolidating UTXOs during periods of low network congestion is often a smart long-term strategy.

The Mempool: Bitcoin’s Waiting RoomThe Mempool: Bitcoin’s Waiting Room

When you send a Bitcoin transaction, it does not immediately appear in the blockchain.

It first enters the mempool. You can think of the mempool as a giant waiting room shared by thousands of nodes around the world. Valid transactions wait there until a miner chooses to include them in a block. Because block space is limited, miners generally prioritize transactions offering the highest fee rate per unit of space.

There is no central authority assigning priority.

There is simply an open market where users compete for limited space inside blocks.

Understanding this mechanism helps users make better decisions about when to transact and how much fee they should pay.

Transparency Has ConsequencesTransparency Has Consequences

So far, we have discussed how Bitcoin works. Now we arrive at something arguably even more important: privacy. One of the most common claims about Bitcoin is that it is anonymous.

It is not.

Bitcoin is pseudonymous.

Addresses do not contain names or identification numbers, but every transaction is public, permanent, and visible to anyone willing to look.

That means anyone can inspect the transaction history associated with a specific address. What makes this particularly interesting is that the blockchain analytics industry has spent years developing techniques to connect seemingly unrelated addresses.

These techniques rely on behavioral patterns, transaction analysis, and address grouping methods known as clustering.

For example, when multiple addresses appear together as inputs in the same transaction, there is often a strong indication that they belong to the same person.

When thousands of similar observations are combined, remarkably detailed maps of economic activity can emerge. There is no magic involved. It is simply data analysis.

The Mistake Most People Still MakeThe Mistake Most People Still Make

During the presentation, I shared a statistic that caught my attention.

Based on historical address reuse analysis, approximately 78% of current outputs have been used more than once.

That number should make us pause.

Bitcoin users have been discussing privacy for more than fifteen years, yet a large majority still reuse addresses.

Why is that a problem?

Because every reused address creates additional visible connections for anyone observing the blockchain.

If you receive your salary at one address and later use that same address for client payments or personal transactions, you are making it easier for others to build a complete picture of your financial life.

Different people begin seeing different fragments of the same story.

And the more fragments that become available, the easier it becomes to reconstruct the entire puzzle.

The good news is that the solution is incredibly simple.

Use a new address every time you receive a payment.

Modern wallets generate fresh addresses automatically.

Unfortunately, many users either ignore this feature or continue sharing old addresses out of habit.

The KYC EffectThe KYC Effect

The situation becomes even more interesting when we introduce KYC (Know Your Customer) procedures.

When you purchase bitcoin through a regulated exchange, that platform knows your identity.

• It knows your name.
• It knows your documents.
• It knows which addresses you used to withdraw your bitcoin.

This does not imply anything illegal or inherently negative. In many jurisdictions, KYC is a standard legal requirement.
However, it does mean that a connection exists between a real-world identity and specific on-chain activity. From that point forward, privacy largely depends on user behavior.

Buying bitcoin is not enough. Moving it to a self-custody wallet is not enough either. Users must understand what information they reveal every time they create a transaction.

Privacy Is Not a Feature—It Is a PracticePrivacy Is Not a Feature—It Is a Practice

Perhaps the most important lesson from the entire presentation is this:

Privacy in Bitcoin is not a button you can switch on.

It is not an automatic property of the protocol. It's practice.

• It depends on how we manage addresses.
• It depends on how we spend UTXOs.
• It depends on whether we separate personal, business, and public identities.
• It depends on how well we understand the tools we use.

Bitcoin’s blockchain is transparent by design. That transparency is precisely what allows anyone to verify that no one can create bitcoins out of thin air or rewrite transaction history. But that same transparency demands more awareness from users.

Rounding up..Rounding up..

Bitcoin is often described as a tool for financial sovereignty.

I agree with that definition—but with one important condition.

Sovereignty is not merely about holding your own private keys.

It is also about understanding the consequences of your actions.

• Understanding what you sign.
• Understanding what you spend.
• Understanding what information you reveal.
• Understanding how the system actually works.

Because in the end, Bitcoin does not reward those who blindly follow trends or chase the next market narrative. It rewards those who take responsibility for understanding the money they choose to use.