The objective of the internship is to familiarize the student with modern cosmology and particularly with the physics, informational content, as well as practical applications and observations of the fluctuations of the cosmic microwave background (CMB). The student will explore different observational techniques and approaches used for observations of the CMB and critically compare them. The student will learn to use and compare multiple numerical codes developed by the community in order to generate simulated maps of the CMB sky and explore the impact of beam effects on them. Later the student will work on a development of a Python code visualizing the CMB sky from a perspective of an internal observer.