John Stamos and Caitlin McHugh Stamos share son Billy, 4.

John Stamos appreciates the "little moments” he shares with his son Billy.

The Fuller House star, who is 58 years old, posted a trio on Instagram of cute pictures featuring his 3-year-old son. It was a reflection on small, but significant moments with Billy.

The first photo shows Stamos sitting in a garden with Billy, while he holds him on his lap and the two of them laughing. A sweet photo of the dad-of-one kissing his son was also taken. The preschooler is wrapped in a towel and hanging out outside with his dad.

"The small moments. These are the'micro-transactions,' which occur between major life events. "Those are my favorite," Stamos wrote in the thoughtful caption.

Stamos' fourth birthday was celebrated by his family with a trip at Discovery Cube's Bubblefest.

He shared photos from the celebrations on Instagram, showing Billy smiling as he enjoyed the bubble-filled room. Stamos's wife Caitlin, Alaina, Josh Peck, and many others joined the father-son team.

"Celebrating an early 'Billy Birthday" courtesy of his beautiful auntie @alainastamos & @thediscoverycube. We loved #bubblefest! THANK YOU for a Wonderful Day!" The proud dad captioned his post.