A temporal sequence of events measured at discrete points in time.
Time series analysis uses methods to extract meaningful information and statistics about a particular time series.
Time series forecasting uses the results of time series analysis to predict future events. For example, a temporal observation set of stock closing prices represents a time series, while time series forecasting is an attempt to predict a future closing price of that stock.
Time series can be uniformly sampled (one observation every day) or event based (one observation each time a trade is done, like tick by tick tapes). The techniques to work with these two stochastic processes of different nature are not the same.