Obtaining approximate solutions to important optimization problems, from combinatorial optimization problems to more general mathematical optimization problems, is sometimes the best one can do. Optimization problems pervade not only theoretical computer science, but many other areas of computer science and applied sciences, implying that fast and nearoptimal solutions are essential to many researchers in different fields. I am interested in the design and analysis of approximation algorithms for optimization problems. The type of optimization problems I am interested in varies from combinatorial problems to problems from stochastic optimization both in the offline and online setting.