Definition: This is a guide set by SMTPE (Society of Motion Picture & Television Engineers) that determines the specific areas on the screen where text and other information should be placed within so that they are not cropped by the viewers’ displays. This guide is continuously updated as displays are updated such as for larger screens and mobile devices.

“Make sure that the titles and captions are within the safe margins of mobile devices.”

Source: https://eks.tv/title-safe-still-matters/