Surface plasmons or surface plasmon polaritons [as the preferred term in the text] are used to investigate small scale phenomena at the interfaces between a metal and a non-metal. The diverse topics described by the book continue work done by Kretschmann et al in the 1970s. That latter work involved using the production of surface plasmons to measure the dielectric constant as a function of the frequency of incident light. Where the light created a resonance at the interface, that produced surface plasmons.
Much of the book's ideas can be understood as related. Though the geometries studied are now more varied. Especially noteworthy is the use of metallic tips, at which SPPs are made. The tips function as probes of nearby materials. Where the length scales are small compared to the wavelengths of the exciting light.