My talk deals with invariants of binary forms of degree 7. Binary forms are homogeneous polynomials in two variables with complex coefficients. We denote by R_d the ring of invariants of binary forms of degree d. People studied intensively the structure of R_d in the 19th century, trying to answer the question "Is the ring R_d finitely generated over C for any d ?". David Hilbert answered this question with his two brilliant papers published in 1890 and 1893: "YES". However, until today, people were able to give a system of generators for R_d only for a few cases: for 2 ≤ d ≤ 8. The case d = 8 was solved in 1967 by Shioda. I will speak in my talk about systems of generators for R₇.