Plain-English definition
Before a transaction makes it into a block, it sits in the mempool, broadcast to the network but not yet confirmed. It is the held breath between sending and settling.
The mempool is public, which means anyone can watch pending trades and try to act ahead of them. That visibility is the soil in which MEV grows.
Why it matters
Mempool matters because crypto markets can look precise while still being shallow, crowded, or poorly sourced. A useful read is not just the number. It is the number, the size behind it, the context around it, and the part it cannot explain.
Simple example
A simple Mempool example is a reader comparing two venues with the same headline price but different depth. The deeper venue can absorb more capital before the trade, peg, or yield reading starts to move against the user.
How Bathymark uses this term
Bathymark uses Mempool to translate open market data into live liquidity readings. When the term touches a live page, the reading links back to the relevant chain, protocol, stablecoin, DEX, perps, or Signal so the source remains checkable.
Common mistake
The common mistake is treating Mempool as a complete signal by itself. Bathymark treats it as one instrument: useful when read beside liquidity, source, size, and what the number cannot prove.