Open interest counts contracts that remain open. It says nothing on its own about who is buying or selling, and reading it as a directional signal is a common mistake.
Open interest is the number of option or futures contracts that are still open at the end of a session. It rises when new positions are created and falls when existing positions are closed.
Every contract has two sides
Each open contract has a buyer and a seller. A rise in open interest at a strike tells you that more contracts exist there. It does not tell you whether the new positions were opened by buyers expecting a move or by sellers expecting the price to stay put.
Reading it alongside price
Analysts usually look at open interest together with price and volume. Rising price with rising open interest is often described as new positions being added in the direction of the move. These are descriptions of what happened, not forecasts.
Where it misleads
Large open interest at a strike is sometimes called support or resistance. Positions can be hedged elsewhere, rolled to the next expiry or closed within minutes, so the level can lose relevance quickly, especially close to expiry.