Spencerian Script is a script style that was used in the United States from approximately 1850 to 1925 and was considered the American de facto standard writing style for business correspondence prior to the widespread adoption of the typewriter.
Platt Rogers Spencer, whose name the style bears, used various existing scripts as inspiration to develop a unique oval-based penmanship style that could be written very quickly and legibly to aid in matters of business correspondence as well as elegant personal letter-writing.
Spencerian Script was developed in 1840, and began soon after to be taught in the school Spencer established specifically for that purpose. He quickly turned out graduates who left his school to start replicas of it abroad, and Spencerian Script thus began to reach the common schools. Spencer never saw the great success that his penmanship style enjoyed because he died in 1864, but his sons took upon themselves the mission of bringing their late father's dream to fruition.