That software moves the world is a clear fact. And that it is becoming more and more important, too. However, not everything is positive in the support that software provides to our daily lives. There are estimates that ICT will be responsible for 20% of global energy consumption by 2030, part of which will be due to software. In this seminar we will review different concepts related to software sustainability. We will look at the two main perspectives of the relationship between software and the environment. We will show some results of software consumption measurements that we have carried out: on the one hand, cases carried out to raise awareness in society in general about the impact that software has on the environment through examples of software intensively used; On the other hand, examples related to software and software engineering carried out with the aim of creating a set of best practices for the software professionals. Our ultimate goal is to make you aware of the consumption problem associated with software and to ensure that, if at first, we were concerned with the "what" and later with the "how", now it is time to focus on the "with what".