Apply Caulk to Seal Gaps and Fill Holes

What happens here

With the baseboard secured and shims trimmed, the man now uses a Milwaukee caulk gun to apply a continuous bead of white caulk. He carefully runs the caulk gun along all the seams where the baseboard meets the wall, where the baseboard meets the door frame, and around the pet door frame. He also applies small dabs of caulk over any visible nail holes to fill them, creating a uniform and sealed surface.

Goal: Seal all gaps and conceal nail holes, preparing the trim for a finished look.