# Overview

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These docs are deprecated and may be outdated. Please use the new docs: [docs.ostium.com](https://docs.ostium.com/)
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Ostium enables traders to take on long or short, leveraged, virtual price exposure to a variety of underlying assets. The protocol enables this by coordinating interaction between Traders, Liquidity Providers, and Protocol Services:

* **Traders,** who are exposed to price variation and PnL changes as a function of their positions.
* **Liquidity Providers,** deposit USDC into the Vault (minting OLP) and act as the market-making counterparty for traders’ positions.
* **Protocol Services,** including pull oracle and automation services operated by partner networks to fetch asset prices and trigger automated orders (e.g., liquidations, limit orders).

## Fees

The protocol charges one-time and compounding fees, on opening and holding a trades, respectively. At closing, no fee is charged, except in cases of liquidation. Variable fees seek to mitigate risks, and can change based on position size, OI Imbalance, volatility, and more.

We break down fees by action as follows:

* [Opening Trades](/ostium-docs/ostium-trading-engine/opening-trades.md)
* [Holding Trades](/ostium-docs/ostium-trading-engine/holding-trades.md)
* [Closing Trades](/ostium-docs/ostium-trading-engine/closing-trades.md)


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