Where an order actually meets another order
A venue is not a logo on a chart. It is the place that holds the book, runs a matching engine, and hands the trade to clearing. Matching pairs a buy and a sell into a trade. Clearing stands between the two sides so each faces the clearing house. Settlement is the later exchange of cash and the instrument. Mixing those three words up is how people think a filled order is already "paid and done."
CME Group
CME Group lists futures and options on equity indexes, rates, FX, energy, and other underlyings, and it clears those contracts. When someone says "the ES" or "the NQ," they mean a specific futures contract on that complex, with a multiplier, a tick, and an expiry. The chart is not the S&P 500 cash index itself.
ICE
ICE is a group of exchanges. In this course the name matters because of energy, including Brent crude, and because of several index and data businesses. Brent is a different oil benchmark from the crude contract that trades on CME. Same word "oil," different specification.
Eurex
Eurex is the main European venue for interest-rate and equity-index derivatives. A Bund future and a Euro Stoxx future are Eurex products. Their session and their holiday calendar are not the New York cash calendar.
Nasdaq, NYSE, and the London Stock Exchange
These are cash equity venues. Their matching engines keep a central limit order book: bids, offers, and a set of priority rules, often price then time. A print on the tape is a match. The displayed quote is what was willing to trade at that moment, not a promise that the same size will be there a second later.
Crypto venues
A centralized crypto exchange also runs an order book and matches bids and offers. A decentralized pool holds inventory and lets traders swap against that inventory. Both can show a last price. Only the order book has a visible queue. A pool's price comes from the ratio of assets in the pool, and size moves that ratio.
