symmetric monoidal (∞,1)-category of spectra
An (finitary) essentially algebraic $(\infty,1)$-theory is an (∞,1)-category $T$ with (finite) (∞,1)-limits.
An algebra over an essentially algebraic $(\infty,1)$-theory in some (∞,1)-topos $\mathcal{X}$ is a (finite) $(\infty,1)$-limit preserving (∞,1)-functor
algebraic (∞,1)-theory, essentially algebraic $(\infty,1)$-theory
Algebras over essentially algebraic $(\infty,1)$-theories that play the role of structure sheaves of algebras are considered in