In 1995 Mayor and Queloz, from the University of Geneva, found the first exoplanet orbiting a main-sequence star. Since then, and with the arrival of large-scale planet finding campaigns, the number of known exoplanets and the variety of known planet host-stars have been growing very fast. We count with 760 confirmed exoplanets ranging from "super Earths" up to "hot Jupiters", orbiting not only around Sun-type stars, but also late active or even early pulsating stars.
I will start with an introduction into the planetary science from an observers point of view: how exoplanets are discovered, detected and studied afterward. I will also discuss about the status of the search for life in other planets. The second part of my talk will be devoted to describe the work I am performing during my PhD in the system WASP-33 and others.