Zeolites are widely used as adsorbents, catalysts, ion exchangers and molecular sieves. However, less is known about the potential use of zeolites and related microporous solids for tailored synthesis of advanced materials. Zeolite-based host-guest nanocomposites are a type of advanced material in which zeolites act as hosts for encapsulating and organizing molecules, crystalline nano-phases and supramolecular entities inside the zeolite pores. Space confinement and host-guest (electrostatic) interaction results in composite materials possessing novel optical, electronic and magnetic properties. Potential technological applications can be expected in a number of fields, such as chemical and biological sensing, semiconductor devices and photonics, to name only a few examples. A related aspect is the fine tuning of the intracrystalline space in zeolites for controlling intrazeolite chemical processes, including the conversion of zeolite cavities into chiral chambers which act as very selective catalysts for the asymmetric synthesis of fine chemicals. Developments in all of these fields critically depend upon improved methods for zeolite characterization and for studying intrazeolite chemistry. For both of these purposes many instrumental techniques are currently being used. Among them, IR spectroscopy deserves special attention. Recent advances in IR spectroscopy of zeolites include the use of variable temperature procedures, synchrotron IR radiation and ultrafast time-resolved IR spectrometry. Examples are given of how IR spectroscopy is strongly contributing to an improved understanding of zeolites and intrazeolite chemistry, which is needed in order to extend potential applications of zeolite-based materials.