What is a CRE portfolio?

Excuse me, could you please elaborate on what a CRE portfolio is? I'm not entirely familiar with the term, and I'm curious to learn more about it. Is it related to cryptocurrency or finance in some way? How does one go about building and managing a CRE portfolio? Are there any specific strategies or considerations that one should keep in mind when constructing such a portfolio? I'd appreciate any insights you could offer on this topic.