National 3-D Day is observed annually on March 17, falling on the third day of the third week in March. This holiday is dedicated to celebrating 3-D technology and its various mediums, which have become increasingly common. It recognizes the perception of depth that arises from the slightly different perspectives of our two eyes, a concept that has been explored since the early days of stereo drawings. The day is marked by appreciation for advancements in 3-D technology, including movies, comic books, and virtual reality. Activities may include engaging with 3-D media, attending events, or exploring the history and development of stereoscopic images. National 3-D Day is observed in the United States and aims to highlight the significance and impact of 3-D technology in modern entertainment and communication.