What is a Mempool?

If you have ever sent an NFT, crypto or funds to another wallet you may have unknowingly used a mempool. But have you ever considered where your transaction is during that delay?

KEY TAKEAWAYS:

— A mempool is a blockchain node’s waiting room for queued and pending transactions.

— There isn’t just one mempool for a blockchain, but many – one for each node on the network.

— A transaction is only included in a block on the chain after it has been verified and approved in the mempool.

Especially if you are new to this crypto space it can be very stressful to wait for your pending transaction.

Did it work?” or “Has my transaction failed? The moment you send your transaction, the transaction is placed in the Mempool. But, what is it and how does it work?

Like more terms in the crypto world, you can easily explain it by splitting the terms. In this case into 'Mem' and pool. Which is derived from 'Memory' and 'pool'.

What is the Mempool?

A mempool is a blockchain node’s version of a waiting room for not-yet-approved transactions. Once you initiate it, your transaction automatically joins the queue in the mempool, before being processed on the blockchain.

What is the Purpose of a Mempool?

Mempools play a crucial role in the operation of a blockchain node. To elucidate, the process of confirming a transaction on a blockchain entails incorporating it into a newly generated block. However, this task isn't accessible to all network participants. In the case of proof-of-work blockchains like Bitcoin, only cryptocurrency miners possess the ability to create blocks. Conversely, in proof-of-stake blockchains like Ethereum, block creation is the prerogative of validators.

Therefore, when you initiate a transaction, you must depend on either a miner or a validator to include it in a block and disseminate it throughout the network. Nevertheless, there can be a delay between your transaction's authorization and its distribution to the network. During this interim period, the transaction requires a temporary holding area, which is commonly referred to as the mempool.

How does the Mempool work?

It's essential to understand that each blockchain doesn't have just a single mempool. In actuality, there exists a mempool within every node on every blockchain, and they each receive distinct transactions at various times. Now, let's delve into the mechanics of this process:

Transactions within a mempool can be in one of two states: queued or pending. A queued transaction transitions into a pending state once the nodes within the network validate it. Subsequently, miners are exclusively permitted to include pending transactions in a block.

Consider this scenario: you decide to send 1 ETH to a friend. You input your friend's wallet address, specify the gas fee, and click the "Send" button. At this juncture, your transaction enters your mempool as a "queued" transaction. From there, it circulates throughout the network of nodes but remains unincorporated into the blockchain.

Instead, each node undertakes verification processes to ascertain the validity of the queued transaction. If no issues are detected by the nodes, the transaction transitions from "queued" to "pending" status. At some point, a miner or validator will retrieve the pending transaction from their node's mempool and incorporate it into a newly created block. Consequently, your transaction is validated, and your friend receives the 1 ETH. Subsequently, the remaining nodes synchronize to remove the transaction from their respective mempools.

Why is my transaction still in the mempool?

This can have several reasons:

- Network Congestion
- You set the gas fees too low
- The Hash Rate drops

How to remove my transaction from the mempool?

- Cancel the transaction? NOTE: it will cost transaction fee.
- Speed the transaction UP. NOTE: This causes additional costs
- Wait a Bit Longer