In the autumn of 2023 we are teaching an online course about theory, fitting and applications of EoS, organized by the Mineralogy Laboratory of the Dept. Earth Sciences & Environment, University of Pavia. The course is designed for masters and PhD students in Earth Sciences, Physics, Chemistry and Engineering but postdocs and researchers are also welcome. The course will provide research students with an understanding of the theory of Equations of State of solids and the methods to critically analyse data to determine the parameters of EoS by using the EosFit software. On completion of the course students will be able to evaluate elasticity and diffraction data for EoS, determine PV and PVT EoS from the data, and calculate the properties of minerals from their EoS. The course will be taught in English. No prior knowledge is required of elasticity or EoS. A normal level of mathematics for PhD students in sciences will be assumed. The course will consist of 24 lectures of 90 minutes held twice a week, normally on Tuesdays and Thursdays. You can receive 11 credits through the European Credit Transfer System (ECTS) by completing the course including the question sheets and passing the final written exam. The course is free, but numbers will be limited. Registration closed on October 15th, and the course is now full.