Star clusters are groups of stars that formed from the same molecular cloud, at the same distance, of the same age, varying only in mass. They are unique objects for which we can find stellar parameters using the Hertzsprung-Russell diagram. Gaia is an ESA astrometric and photometric survey to study a billion stars of our Galaxy. We shall study the importance of using Gaia data to study star clusters. The lecture will be given in the first hour, and interested people are welcome to attend only this part. In the second hour, a hands-on session using TopCat will demonstrate the use of Gaia data for analysis of star clusters and will be used to find the distances to a known star cluster. Students participating in the hands-on session are requested to use their laptops (with TopCat installed, http://www.star.bris.ac.uk/~mbt/topcat/) during the second part of the session.
