Time series analysis is the study of data recorded in order — how observations depend on the ones before them, and how that dependence can be turned into a description and a forecast. It runs from the components a series is made of (trend, seasonality, noise), through stationarity and the autocorrelation function, into linear time-domain models, the frequency-domain view, nonstationary and seasonal models, volatility models for financial data, and state-space form. Nano College takes the standard university treatment of this subject and rebuilds it as short, self-contained pieces: each article can be read and finished on its own, with the rigour kept and the padding removed. Working through them leaves you able to choose a model class, estimate it, check whether it survived contact with the data, and attach a defensible error to the forecast.