> ## Documentation Index > Fetch the complete documentation index at: https://pmxt-sync-hosted-docs.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Prediction Markets 101 > What a prediction market is, what an outcome is, and what 'price' means here. A glossary for engineers landing in prediction markets for the first time. Skim it once; come back when an unfamiliar term shows up. ## Core concepts ### Prediction market A market where the traded asset is a share in a possible future outcome. The share pays $1 if the outcome resolves true and $0 if it resolves false. Example: a "Yes" share on *"Will the Fed cut rates in March?"* pays \$1 if the cut happens. ### Event, Market, Outcome PMXT's catalog is three levels deep. An **Event** is a real-world question ("2024 US Presidential Election"). A **Market** is a specific tradable framing of that event ("Will Trump win the 2024 election?"). An **Outcome** is a single side of the market ("Yes" or "No"). One event can have many markets; one market always has two or more outcomes. See [Unified schema](/concepts/unified-schema) for the schema-level detail. ### Price as probability Outcome prices are in the closed interval \[0, 1] and are read as the market's implied probability that the outcome resolves true. A "Yes" share trading at 0.31 pays \$1 if Yes resolves true, so the market is implying a roughly 31% chance. The "Yes" price plus the "No" price for a binary market sum to approximately 1 (minus venue spread). ### Catalog UUID vs venue ID PMXT assigns its own stable UUID to every market and outcome. The underlying venue (Polymarket, Kalshi, etc.) also has its own native ID — a hex condition ID, a ticker, a hash. The hosted trading API accepts either — pass whatever your code already has; the SDK picks the right wire field. Cross-venue identity (Router results, portfolio analytics) is the place where the catalog UUID matters. See [Catalog UUID vs Venue ID](/concepts/catalog-uuid-vs-venue-id). ## Crypto / EVM terms (for the non-crypto reader) ### Wallet An on-chain account, identified by a public address (e.g. `0xAbc...`). It can hold tokens and sign transactions. A wallet is controlled by a **private key**. ### EVM private key A 32-byte secret that controls a wallet address on any Ethereum-compatible (EVM) chain. The same key works across Ethereum, Polygon, BSC, Arbitrum, and other EVM chains — the address derives from the key, not the chain. PMXT only uses your private key for local signing; it never leaves your machine. ### Polygon A specific EVM-compatible chain (chainId 137). PMXT's `PreFundedEscrow` contract and Polymarket's CLOB exchange both live on Polygon. This is the only chain you fund. ### USDC A US-dollar-pegged stablecoin (1 USDC ≈ \$1) issued on many chains. PMXT hosted trading settles in **USDC.e on Polygon** (`0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174`) — the bridged token Polymarket's CTF exchange uses. Native Polygon USDC and bridged USDC on other chains are not interchangeable. ### EIP-712 The typed-data signing standard PMXT uses for hosted writes. Instead of signing an opaque hex blob, your wallet signs a structured payload with named fields — making the signature human-auditable and replay-resistant. Every hosted order, cancel, and escrow action is an EIP-712 signature. See [Signing](/guides/signing). ### PreFundedEscrow The non-custodial smart contract on Polygon that holds USDC for hosted trading. You deposit USDC once; subsequent trades spend from the escrow balance until you withdraw. Funds can only move against an EIP-712 signature from your wallet, so your wallet retains beneficial ownership the entire time. See [Hosted Trading](/concepts/hosted-trading) and [Escrow Lifecycle](/guides/escrow-lifecycle). ## Trading terms ### CLOB Central Limit Order Book. The matching-engine model where bids and asks are stored in a sorted book and orders match against the best available price. Most prediction-market venues (Polymarket, Kalshi) run a CLOB. ### Market order An order that executes immediately at the best available price, walking the book until filled. You specify size, not price. Set a generous `slippage_pct` to bound the worst price you'll accept. ### Limit order An order that rests on the book at a specified price and only executes when a counterparty crosses it. You specify both price and size. ### Group A methods In PMXT, **Group A** refers to the shared trading and account method surface for venues that implement those capabilities — `create_order`, `fetch_balance`, `fetch_positions`, `fetch_my_trades`, and friends. Method names and response schemas are unified where supported; hosted write support is venue-specific. See [Hosted Trading](/concepts/hosted-trading#whats-supported-today), [Supported Venues](/concepts/venues#feature-support), and [API Reference](/api-reference/overview). ## Hosted vs self-hosted ### Hosted (default) PMXT operates the catalog, the escrow contract, and the venue-submit path. You hold a `pmxt_api_key` and a wallet private key; PMXT does everything else. See [Hosted Trading](/concepts/hosted-trading). ### Self-hosted You run `pmxt-core` on your own machine, supply raw venue credentials, and the SDK talks directly to the venues. No API key, no escrow, no PMXT in the trade path. See [Hosted Trading](/concepts/hosted-trading#when-to-switch-to-self-hosted) for the comparison.