> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rails.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

> Trading options on Rails

All options on Rails are European style that are exercisable only at expiry and cash settled in USDT.
Contract definitions are managed natively by the platform. Following are the key properties of options on Rails.

## Key Capabilities

* **Cash settlement at expiry.** Each contract is settled automatically in cash against
  the settlement price at expiry — there is no manual exercise step and no physical
  delivery of the underlying. See
  [Settlement & Expiry](/latest/options/guides/settlement-and-expiry).
* **Fixed expiries.** Contracts expire on a schedule (weekly and monthly) at
  08:00 UTC.
* **Volatility-based pricing.** Each contract carries a mark price derived from the
  Black-76 model along with implied volatility and a full set of Greeks. See
  [Pricing & Greeks](/latest/options/guides/pricing-and-greeks).
* **Real-time over WebSocket.** Live contracts, quotes, order books, positions, and
  account state are delivered over the [WebSocket](/latest/options/websocket-api/overview).
  A small REST surface covers [account summary](/latest/options/rest-api/get-account-summary),
  [contract listings](/latest/options/rest-api/get-contracts), and
  [pricing](/latest/options/rest-api/get-contract-pricing).

## Core Concepts

| Concept            | Description                                                                                                                                                |
| ------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Underlying         | The asset an option is written on, e.g. `BTC` or `ETH`.                                                                                                    |
| Contract           | A single tradable option, identified by underlying, expiry, strike, and type. See [Instruments & Symbols](/latest/options/guides/instruments-and-symbols). |
| Option type        | `C` (call) gives upside exposure; `P` (put) gives downside exposure.                                                                                       |
| Strike             | The price at which the option settles in or out of the money.                                                                                              |
| Expiry             | The date the contract settles, at 08:00 UTC.                                                                                                               |
| Premium            | The price paid (long) or received (short) to open the position.                                                                                            |
| Greeks             | Delta, gamma, vega, theta, and rho — sensitivities used to manage risk.                                                                                    |
| Implied volatility | The volatility implied by an option's price, quoted for mark, bid, and ask.                                                                                |

## How to Get Started

<Steps>
  <Step title="Set up your account">
    Complete [Get Set Up with Rails](/latest/get-set-up-with-rails) — registering,
    funding, and creating API keys.
  </Step>

  <Step title="Connect">
    Authorize your requests with an access token (see
    [API Authorization](/latest/authorization)) and open a
    [WebSocket](/latest/options/websocket-api/overview) connection.
  </Step>

  <Step title="Discover contracts">
    List available expiries and contracts via the
    [Contracts Stream](/latest/options/websocket-api/contracts-stream) or the REST
    [Get Expirations](/latest/options/rest-api/get-expirations) and
    [Get Contracts](/latest/options/rest-api/get-contracts) endpoints, and watch live prices
    on the [Quotes Stream](/latest/options/websocket-api/quotes-stream).
  </Step>

  <Step title="Trade">
    Place orders on the
    [Order Creation Stream](/latest/options/websocket-api/order-creation-stream/overview),
    then track fills, positions, and balances over their respective streams.
  </Step>
</Steps>