"I Feel Happy: Why Do I Feel Happy Today?" is a children's book in the "First Emotions" series, focusing on teaching young children about emotions. With a publication year of 2020, this board book is illustrated and written by DK, making it an engaging and educational read for toddlers aged 3-5 years. The book covers the topic of social emotions and feelings in a simple and interactive way, making it a valuable resource for young children learning about their emotions and why they feel happy.