Being included matters most to the person who almost wasn’t. Count the chairs before you sit.

Inclusion is felt most sharply by whoever was nearly left out. For most of the group a seat at the table is unremarkable, and for one person it is the whole evening, because they walked in unsure whether there would be room. The cost to you is a chair. The value to them is not proportional to that.

Before you sit down, look at who is standing. Pull a chair over, move the bags, say somebody’s name and point at the space. Thirty seconds of noticing is the most reliably useful thing you can do at a gathering, and almost nobody does it.