Intro to Python for Financial Market Data

Most finance websites show quotes or charts for various financial markets. Where is this data freely available and how can we download it, wrangle it into a useable format, and visualize it ourselves?

A quote for a financial instrument like a stock, currency, or commodity is a snapshot in time reflecting the sum of individual trades happening on the market for this instrument. Data points like price or trading volume are collected periodically to form a historical time series. If we chart this time series, we can visualize the activity of individual instruments, or the market as a whole with an index, and gain a quick overview, and perhaps some insights into the data.

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