Huber rings and valuation spectra

These notes expand a four-hour lecture course given in Heidelberg in March 2023, as part of the “Spring School on non-Archimedean Geometry and Eigenvarieties”. They are designed for graduate students and other learners. We introduce Huber rings and valuation theory alongside frequent examples. The notes are largely self-contained, though many details are given in exercises found following each lecture.