What is a positron, what does it do, where is it used?

We know more or less what electron, proton and neutron are, but have you ever heard of the positron? Considered as the first important example of the concept of a positively charged lepton and antiparticle, tomography devices using positrons enable the hidden tumours in our body to be revealed. Let’s see what a positron is, what it does, where it is used in all details.