The beginning of the twenty-first century stands a good chance of being identified in history as the time when humankind first came to grips with the Universe. In a rush of observational progress, the charge led by the 1992 discovery of cosmic microwave background anisotropies by the Cosmic Background Explorer (COBE) satellite, the elements required to build accurate cosmological models were assembled. Complementing this, development of theoretical methods allowed accurate predictions to be made to confront those observations.

The landmark was the 2003 announcement of precision cosmic microwave measurements from the team operating the Wilkinson Microwave Anisotropy Probe (WMAP). Ironically, this success lay in a kind of failure – a failure to uncover anything new and unexpected. In the words of astrophysicist John Bahcall at NASA's announcement press conference, “the biggest surprise is that there are no surprises”. Instead, then, the power of the observations became fully focussed on determining the properties of the cosmological model, and for the first time many of its components were determined to a satisfying degree of accuracy: the percent level for quantities such as the geometry of the Universe, its age, and the density of the baryonic material, and the ten percent level for many other aspects.

In 2000, we published a graduate-level textbook, Cosmological Inflation and Large-Scale Structure, written during the late 1990s and which described many of the ideas underpinning the modern cosmology.