> Understanding the fundamental building blocks of Polymarket
Every prediction on Polymarket is structured around two core concepts: **markets** and **events**. Understanding how they relate is essential for building on the platform.
| **Condition ID** | Unique identifier for the market's condition in the CTF contracts |
| **Question ID** | Hash of the market question used for resolution |
| **Token IDs** | ERC1155 token IDs used for trading on the CLOB — one for Yes, one for No |
<Note>
Markets can only be traded via the CLOB if `enableOrderBook` is `true`. Some
markets may exist onchain but not be available for order book trading.
</Note>
### Market Example
A simple market might be:
> **"Will Bitcoin reach \$150,000 by December 2026?"**
This creates two outcome tokens:
* **Yes token** - Redeemable for `$1` if Bitcoin reaches `$150k`
* **No token** - Redeemable for `$1` if Bitcoin doesn't reach `$100k`
## Events
An **event** is a container that groups one or more related markets together. Events provide organizational structure and enable multi-outcome predictions.
### Single-Market Events
When an event contains just one market, it creates a simple market pair. The event and market are essentially equivalent.
```
Event: Will Bitcoin reach $100,000 by December 2024?
└── Market: Will Bitcoin reach $100,000 by December 2024? (Yes/No)
```
### Multi-Market Events
When an event contains two or more markets, it creates a grouped market pair. This enables mutually exclusive multi-outcome predictions.
```
Event: Who will win the 2024 Presidential Election?
├── Market: Donald Trump? (Yes/No)
├── Market: Joe Biden? (Yes/No)
├── Market: Kamala Harris? (Yes/No)
└── Market: Other? (Yes/No)
```
## Identifying Markets
Every market and event has a unique **slug** that appears in the Polymarket URL:
Specifically for sports markets, outstanding limit orders are **automatically cancelled** once the game begins, clearing the order book at the official start time. However, game start times can shift — if a game starts earlier than scheduled, orders may not be cleared in time. Always monitor your orders closely around game start times.
