This section introduces the motivation for using geophysics as well as an introduction to what geophysics is. The motivation is introduced by discussing subsurface information needs and approaches to meet these needs. This leads to a discussion about the two types of approaches to meet these needs (invasive and noninvasive), and a high level description of noninvasive imaging in the geosciences (i.e. geophysics) using medical analogues. This section also introduces the concept of timelapse imaging.