Age-metallicity relation for the Auriga sample. In the y-axis we show the median [Fe/H] metal abundance in each stellar age bin and the panels represent the stars in different components (the panel on the left represents all stars). Grey lines represent the curves for all galaxies in the sample, while the solid coloured line shows the curve for the sample average. The dashed line in each panel shows the ±1 standard deviation of the sample average.