equivalences in/of -categories
The collection of spectra form an (∞,1)-category which is in fact a stable (∞,1)-category. Indeed, it is the universal property stabilization of the -category ∞Grpd, equivalently of the simplicial localization of the category Top at the weak homotopy equivalences.
plays a role in stable homotopy theory analogous to the role played by the 1-category Ab of abelian groups in homological algebra, or rather of the category of chain complexes of abelian groups.
In the context of (∞,1)-categories a spectrum is a spectrum object in the (∞,1)-category of pointed topological spaces.
Recall that spectrum objects in the (infinity,1)-category form a stable (∞,1)-category .
The stable (∞,1)-category of spectrum objects in is the stable -category of spectra
With the smash product of spectra becomes a symmetric monoidal (infinity,1)-category.
an algebra object in with respect to this monoidal structure is an associative ring spectrum;
a commutative algebra object in with respect to this monoidal structure is a commutative ring spectrum;
the stable -category of spectra is described in section 9 of
Its monoidal structure is described in section 4.2
That this is a symmetric monoidal structure is described in section 6 of