Bow varieties were introduced by Cherkis as analog of ADHM
type description of instanton moduli spaces on the Taub-NUT space
(C2 with a hyper-Kaehler metric, not a Euclidean one.) We
study these varieties from a more algebro-geometric point of view, and introduce their `multiplicative' analog. Applications are their
identifications with Coulomb branches of 3d and 4d gauge theories
The first part is joint work with Y. Takayama, while the second is with D. Yamakawa.