  We study soft theorems in a broader context, addressing their fate at loop
level and their universality in effective field theories and string theory. We
argue that for gauge theories in the planar limit, loop-level soft gluon
theorems can be made manifest already at the integrand level. In particular, we
show that the planar integrand for N=4 SYM satisfies the tree-level soft
theorem to all orders in perturbation theory and provide strong evidence to
this effect for integrands in N<4 SYM. We consider soft theorems for
non-supersymmetric Yang-Mills theories and gravity, and show the validity of
integrand soft theorem, while loop corrections to the integrated soft theorems
are intimately tied to the presence of conformal anomalies. We then address the
question of universality of the soft theorems for various theories. In
effective field theories with F^3 and R^3 interactions, the soft theorems are
not modified. However for gravity theories with R^2 phi interactions, the
sub-sub-leading order soft graviton theorem, which is beyond what is implied by
the extended BMS symmetry, requires modifications at tree level for
non-supersymmetric theories, and at loop level for N<5 supergravity due to
anomalies. Finally, for superstring amplitudes at finite alpha', via explicit
calculation for lower-point examples as well as world-sheet OPE analysis for
arbitrary multiplicity, we show that the superstring amplitudes satisfy the
same soft theorem as its field-theory counterpart. This is no longer true for
bosonic closed strings due to the presence of R^2 phi interactions.
