We study the interactions of the Higgs boson with other elementary particles, which allows us to explore the mechanism that is responsible for the masses of the fundamental particles. Members of our group lead a measurement of the coupling between the Higgs boson and top quarks, the heaviest known fermions. Furthermore, we develop analysis techniques for future measurements of the Higgs-boson self-coupling. These will help us to probe the shape of the Higgs potential - one of the big open questions in Higgs physics. In addition, we prepare searches for hypothetical heavy Higgs bosons, which - if discovered - would be a direct signal of new physics.