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Function

A function is like a machine. You put something in, and it gives something out. For example, a candy machine: you put in a coin (input), and you get a candy (output). The machine's job is to convert coins to candy.

Trading Example: A Simple Moving Average (SMA) is a function. You input stock prices for the last 'n' days, and it outputs the average price. If you use a 50-day SMA, you input the last 50 days of stock prices, and the function gives you the average of those 50 prices. This helps traders see if the stock is currently above or below its recent average.