This bachelor’s thesis introduces Bernoulli numbers and explores some of their key appli-cations in mathematics. The work begins by examining the classical problem of summing powers of natural numbers, leading to the appearance of Bernoulli numbers as a central component in closed-form expressions for these sums. The thesis then presents the definition and basic properties of Bernoulli numbers, including their representation through generating functions and their connection to Bernoullipolynomials. Several applications are discussed, such as their role in series expansions of elementary functions and in evaluating values of the Riemann zeta function at even integers. Finally, the thesis touches on the use of Bernoulli numbers in the Euler-Maclaurin summation formula and briefly outlines their relevance to number theory, including their historical link to early attempts to understand Fermats Last Theorem.