Abstract: Key to understand the behavior of aerosol particles and their potential impacts on human health and climate is to determine their physical properties, including their concentration, their size and a number of other intrinsic particle properties. The objective of this tutorial is to cover the very basics in aerosol instrumentation by reviewing the operating principles of the most commonly employed particle counters and sizers, and how those can be combined in advanced systems for probing properties such as the morphology, volatility, hygroscopicity and cloud condensation nuclei activity of the particles. Describing how an aerosol electrometer works, we will expand our discussion on the operating principles of optical and condensation particle counters. Furthermore, we will explore how information from optical particle counters can be used to determine the (optical) size of particles larger than ca. 300 nm, aside from their concentration, and investigate how other techniques can lead to similar information (e.g., determining the aerodynamic size of particles larger than ca. 500 nm). Underlining the importance of mobility analysis for sizing particles in the sub-micron range and down to < 1 nm, good part of this tutorial will focus on the operating principle of the Differential Mobility Analyzer, and how different versions of it have become standards in aerosol metrology. The tutorial will close by providing an overview of systems for determining other intrinsic particle properties, as listed above, and how those can be operated in field observations. Participants in this tutorial will get the change to gain hands-on experience by employing a number of instruments for characterizing the ambient aerosol that will be available on site.