Outline for lectures on string topology for stacks Overview: the first lecture will introduce the notion of geometric and topological stacks and the construction of the bivariant theory for topological stacks. The second lecture will deal with algebraic structures on (co)homology of stacks focusing on string topology. In particular we will develop the required notion of mapping stacks, orientation for stacks and cover some examples (including some specific to stacks such as inertia stacks). Detailed plan of the lectures: First lecture: I) About Topological and Differentiable stacks: A) Definitions and Examples: introduce the notion of differentiable stacks (or geometric stacks) and give classical examples such as the classifying spaces of groups viewed as a stack, orbifolds. Explain the relationship with groupoids. B) Vector bundles on stacks: explain how to generalize the notion of vector bundles to stacks. The issue with tangent bundles shall be mentioned. II) Algebraic topology for (topological) stacks: Introduce the notion of topological stacks focusing on why they are a good notion for stacks with which to algebraic topology. In particular, explain why they have a well-defined homotopy type, singular (co)homology theories. Possibly, one shall recall the link with equivariant (co)homology. III) Bivariant Theory for topological stacks: A) Explain what is a bivariant theory: the categorical setup and axioms. Explain the slight generalization needed in the case of stacks. B) Gysin maps associated to bivariant theory. Describe how one can construct Gysin maps in (co)homology and explain what kind of functoriality they get. C) The bivariant theory for stacks: Explain the definition, construction and link with singular homology. The examples of Gysin maps in equivariant homology shall be given if time permits. References for part I are String Topology for Stacks, Parts 1,2,3 as well as Behrang Noohi's Introduction to Topological Stacks or Behrend and Xu's paper on differentiable stacks and Moerdijk and Mrunc's book on Lie groupoids. Additional references for part II are Behrend's paper on cohomology for stacks (ICTP lectures notes) and Noohi's paper on homotopy type for paratopological stacks. Fulton and MacPherson's book "Categorical framework for the study of singular spaces", memoir of the AMS, is the important reference for bivariant theory. Second lecture: I) Orientation for stacks: Introduce the notion of nns map, the link with orientation and give the key example. II) Mapping stacks: Definition of the mapping stack as a stack over Topological spaces and explain the condition under which it is a topological stack. Introduce the notion of Hurewicz stack and explain why it solves the problem of Map(-,Y) not commuting with pushouts. Give a groupoid presentation for loop stacks. III) Applications and Examples: A) Explain the construction of the loop product first and maybe its instance for ghost loops and or sphere product... B) Explain Poincaré duality and intersection pairing for orbifolds. Introduce the inertia stacks as the ghost loop stack. Explain the intersection pairing and gave its relationship with Chen-Ruan cup-product. C) Explain the others string topology operations for stacks. D) Compute the example of the Frobenius structure for classifying stack of compact Lie groups.