Pseudo-Bosons, So Far

In the past years several extensions of the canonical commutation relations have been proposed by different people in different contexts and some interesting physics and mathematics have been deduced. Here, we review some recent results on the so-called pseudo-bosons. They arise from a special deformation of the canonical commutation relation [ a , a † ]   =   ll , which is replaced by [ a , b ]   =   ll , with b not necessarily equal to a†. We start discussing some of their mathematical properties and then we discuss several examples.