**2. Key Questions That Can Be Addressed with GRB Polarization**

Measurements of the prompt GRB polarization may help shed light on many critical aspects of the relativistic outflow whose knowledge has evaded us so far. Below, we summarize key open questions in GRB physics, which can be probed with spectro-polarimetric observations. More detailed reviews and discussions of these topics can be found in other review articles (e.g., [25–29]). Theoretical modeling of prompt GRB polarization and comprehensive results are provided in Section 4.
