What is a Liquidity Pool?

The so-what: In a traditional market, to buy a token, someone else has to be selling it to you at that exact moment. In DeFi, you trade against a smart contract containing a giant bucket of pooled assets. That bucket is a liquidity pool.

The vending machine analogy

Think of a liquidity pool as a vending machine. Instead of waiting for a person to sell you a soda, you just insert your money and the machine spits out a drink.

DeFi liquidity pools work the same way. Liquidity providers deposit pairs of tokens (like SOL and USDC) into the machine. Traders put in SOL to take out USDC, or vice versa, paying a tiny transaction fee to the pool owners for the convenience.

Nobody has to agree to your trade. The machine will always quote you a price, at three in the morning, for any size, as long as there is something in it.

How the machine sets its price

The classic design keeps the two sides multiplied together at a constant. If the pool holds 1,000 SOL and 100,000 USDC, then SOL is priced at 100 USDC because that is the ratio between the two piles.

Take SOL out and there is less SOL left, so the remaining SOL gets more expensive. Put SOL in and it gets cheaper. The price is nothing more than the ratio of what is inside, and every trade nudges it.

Two useful consequences fall out of this. Slippage: a big trade moves the ratio while it executes, so you get a worse average price than the screen quoted. And arbitrage: if the pool drifts from the wider market, traders profit by correcting it, which is the mechanism that keeps the pool honest without anyone supervising it.

What you actually deposit

A classic pool takes both sides in equal value. To add $1,000 to a SOL and USDC pool you need $500 of each, not $1,000 of one.

This catches people out constantly. Holding $1,000 of SOL and nothing else does not make you ready to join a SOL and USDC pool. Half has to be sold first, which is a real trade with a real cost, and it happens before you earn a cent.

On Solana you also need a little SOL left over for network fees and for the account rent that holding new tokens requires. Spending your last cent on the deposit is a reliable way to have it fail.

What you get back, and why your wallet looks empty

When you deposit, the pool issues you an LP token. It is a receipt that says what share of the pool is yours. Burn it later and you get your share of whatever is in there at that moment, fees included.

Here is the part nobody warns you about. That LP token is usually just an ordinary token with no logo and no listing, so your wallet will often show it as an unknown asset, or not show it at all. People conclude the deposit failed and try again, sometimes depositing twice.

It did not fail. Look up the transaction on a block explorer and you will see the two tokens leave and the LP token arrive. The position is real and on-chain whether or not your wallet has a picture for it.

Where the fees go

Every swap pays a fee, commonly between 0.01% and 1% depending on the pool. Those fees are added straight back into the pool, which means your share is quietly worth slightly more each time somebody trades.

In a classic pool you do not claim them and there is nothing to harvest. They are already yours, folded into the balance you will withdraw. That is also why a pool position with no trading volume does nothing at all: no swaps, no fees, no growth.

Concentrated liquidity, briefly

Newer pools let you choose a price range instead of covering every price from zero to infinity. Inside that range your capital works much harder and earns a bigger share of fees.

The catch is that when the price leaves your range you stop earning entirely and end up holding only the losing side of the pair. It is a genuinely more efficient design and a genuinely more demanding one, because it needs attention rather than patience.

How you get out

You withdraw by burning the LP token, and you receive your share of both sides as they stand that day. Note that this is both sides: you rarely get back the same quantities you put in, because the ratio inside has shifted with the market. That shift is impermanent loss, and it is the main thing to understand before joining a pool.

What can actually go wrong

• Divergence loss, covered above, and the most common disappointment.
• Smart-contract risk. Your money sits in code. Audited, widely used pools are not risk-free, they are better-tested.
• One token collapsing. A pool will keep buying a falling token with your good one, so it converts you into the loser on the way down.
• Fake pools. Anyone can create a pool for any token, including one that looks exactly like a real one. Check the pool address, not the name.

Try it with numbers first

Estimate fee income with the free LP Profit Calculator, then check it against the Impermanent Loss Calculator. A pool is worth joining when the first number comfortably beats the second.

FiLot is an analysis and bookkeeping tool, not financial advice. Providing liquidity can lose money, including all of it.

Next: what non-custodial means, and what it stops anyone from doing to your funds.