Creating Scratch layer gives me a choice between Polygon and Multipolygon, so I started wondering how should I make use of them.

Reading a new book "Mastering QGIS" (through this answer by Joseph), authors' comment was "ESRI shapefiles store geospatial data in multi- type geometry, so using multi- type geometry is a good practice if you plan on converting between formats."

How should I choose one of them (Polygon or Multipolygon) when I create a new polygon layer? (I had confused multi-polygon with multipart-polygon, so I used to choose Polygon.)