Why was it know as the silent film era?

During the silent film era (roughly from the late 1890s to the late 1920s), produced films contained no synchronized dialogue, or audible speech, and instead relied heavily on visual storytelling, acting gestures, title cards, and music to communicate the story and convey emotions.

Few early films included synchronized sound effects or music due to technological limitations, and sound-on-film technology was still under development. Some theaters provided live musical accompaniment.

The term "silent film era" emerged as a way to distinguish the early period of filmmaking from the "talkie era" that began with the introduction of synchronized sound technology.