The articles in this volume are devoted to: - moduli of coherent sheaves; - principal bundles and sheaves and their moduli; - new insights into Geometric Invariant Theory; - stacks of shtukas and their compactifications; - algebraic cycles vs. commutative algebra; - Thom polynomials of singularities; - zero schemes of sections of vector bundles. The main purpose is to give "friendly" introductions to the above topics through a series of comprehensive texts starting from a very elementary level and ending with a discussion of current research. In these texts, the reader will find classical results and methods as well as new ones. The book is addressed to researchers and graduate students in algebraic geometry, algebraic topology and singularity theory. Most of the material presented in the volume has not appeared in books before.  Contributors: Jean-Marc Drézet, Tomás L. Gómez, Adrian Langer, Piotr Pragacz, Alexander H. W. Schmitt, Vasudevan Srinivas, Ngo Dac Tuan, Andrzej Weber