In this talk I shall try to outline the subject which will be discussed in detail by the succeeding speakers. I shall concentrate on ideas and I shall not attempt to present any definite results. The two sides to this problem are:

(a) How much helium is there in the Universe?

and

(b) Where and how has it been produced?

I shall sub-divide (a) and (b) into

• (a) (i) Direct observations

  • (ii) Inferences from theories of stellar structure and evolution

• (b) (i) Helium production in stars

  • (ii) Primeval helium production

  • (iii) Production in other objects