What does it even mean
Trading is the business of buying and selling financial products, usually (but not always, e.g. hedging) to make a profit. A trading system is software that allows manual or automated trading activities. It can be a simple graphical interface where the trader can place or cancel an order, or a complex automated multi-service system for trading 24/7 according to specific rules.
An important point to clarify is that building a trading system doesn’t necessarily mean to come up with the trading strategies. Building a trading system is the act of building the infrastructure to implement the strategies (which can be very well known, or proprietary and carefully studied by the quantitative researchers, a.k.a. Quants) for automated trading, or just to facilitate manual trading.
Centralized cryptocurrency exchange (CeFi)
An exchange is a market, where buyers and sellers meet to trade. A crypto exchange is a market where mainly, or only, crypto products are traded.
Crypto products can be cryptocurrencies (the digital coins or tokens, which you can deposit or withdraw from the exchange), or derivative products based on crypto, like futures, perpetual futures and options. Will get in more detail about crypto trading products in another post.
Crypto exchanges can be centralized (CEX) or decentralized (DEX). The main difference is that CEXs are normal web platforms, while DEXs are web platforms based on a blockchain. Without diving into the details (also a topic for another post), we’ll start looking at CEXes because it’s easier to get started this way.