Physics 583 (QFT II) Spring 2021 zoom lecture on Thursday April 29, 2021. today we showed that the O(3) nonlinear sigma model has instantons and D=2 Euclidean dimensions (and Skyrmions in 2+1 dimensions) and constructed the instanton solutions. We then showed that G/H nonlinear sigma models (including the CP^n models) also have instantons if H contians at least one U(1) subgroup. In the second part of the lecture we showd that the Georgi-Glashow model has instantons in D=3 which are the 't Hooft-Polyakov monopoles. We ended the lecture with a discussion of instantons in Yang-Mills theory in D=4 dimensions.