PABU stands for "participatory budget". PABU gives students the opportunity (in addition to the regular "financial applications" and "investments") to implement ideas and projects for the student body. The money for PABU comes directly from the student body's general budget, where it forms a separate budget title.
Every student can submit a proposal for the use of PABU. The special feature of this budget title is that all students of the University of Erfurt are invited to vote on the use of the PABU (for more details on voting see here). The implementation of the proposal with the most votes is submitted to the student council (StuRa) as a resolution.
Every member of the student body at the University of Erfurt can participate - in other words, every registered student. Proposals for the use of PABU can be submitted by individual students or groups of students, university groups or student councils at the University of Erfurt. However, the submitted proposals are represented pro forma by a person studying at the University of Erfurt.