Plots... filling area between two curves?

With Plots – how can I fill the area between two curves/time series? E.g., suppose:

  • I have one time series consisting of pairs (x_i,y_i) with i\in\{1,\ldots,N\} - where y_i could be the expected value of some system,
  • and I have also pairs (x_i,\sigma_i) where \sigma_i could be some standard deviation varying with i.
  • I would then like to produce a plot which is a filled area between curves y_i -\sigma_i and y_i + \sigma_i

How can I do this?

In more general terms, how to fill the area bounded by curves y_1(x), y_2(x), and x=x_a and x=x_b?


Thanks. The ribbon argument is what I needed.