Infectious diseases can inflict immense losses and suffering on the human population. Current pandemic of SARS-CoV-2 (COVID19) virus has already caused more than 2 million cases and nearly 300 thousand excess deaths. The outbreak of influenza in 1918 was an even bigger event, leading to perhaps as many as 100 million deaths worldwide. Diseases such as a bubonic plague, smallpox, measles or Ebola, have been causing many deaths throughout centuries. Animal diseases, such as foot and mouth or African swine fever are limiting our ability to feed the population, and plant and tree diseases like ash dieback, blights or rusts seriously affect our countryside and food security. It is therefore important to be able to predict the course of a disease outbreak, to design effective control measures during the epidemic, and to find ways to prevent the spread. Mathematical modelling has been one of the key tools used to achieve these tasks and to inform governmental policies. In this talk I will introduce some basic concepts of epidemiological modelling, starting with exponential and logistic growth and moving on to the Susceptible-Infected-Recovered model. I will also introduce concepts like “basic reproduction rate” and “herd immunity” and briefly touch upon designing effective control campaigns.