Silent Film
The Jazz Singer (1927) was the first commercially succesful 'talkie', or film that has synchronized sound. By 1930, films that were produced without accompanying sound were becoming more uncommon
Flammability
Nitrocellulose or nitrate film is highly flammable and was used for motion picture film until the 1950s. If a projector was run too slowly, then there was an increased chance that the film could catch on fire due to the exposure of the intense light source utilized for production. Frame rates were not standardized
When 'talkies' were introduced, frame rates became standardized.
"Nitrocellulose was used as the first flexible film base, beginning with Eastman Kodak products in August, 1889. Camphor is used as plasticizer for nitrocellulose film, often called nitrate film. It was used until 1933 for X-ray films (where its flammability hazard was most acute) and for motion picture film until 1951. It was replaced by safety film with an acetate base."
Pantomime
Silent films tend to be over acted.
Intertitles
There were 'scenario writers' and there were 'title writers' --> language and action composed by two different people. Language which was developed verbally first.