He came to New York in 1902 almost unknown. At his death eight years later he was the best known writer of short stories in America. His life was as full of ups and downs, and of strange turns of fortune, as one of his own stories. William Sidney Porter, who always signed his stories as O. Henry, was born in Greenboro, North Carolina, September 11, 1862. His mother died when he was but three years old; and an aunt, Miss Evelina Porter, cared for him and gave him nearly all his education. Books, too, were his teachers. He says that between his thirteenth and nineteenth years he did more reading than in all the years since. His favorite books were The Arabian Nights, in Lane's translation, and Burton's Anatomy of Melancholy, an old English book in which bits of science, superstition and reflections upon life were strangely mingled. Other books that he enjoyed were the works of Scott, Dickens, Thackeray, Victor Hugo and Alexandre Dumas. He early showed ability as a cartoonist, and was noted among his friends as a good story teller. After school days he became a clerk in his uncle's drug store, and here acquired that knowledge which he used to such good effect in stories like "Makes the Whole World Kin" and "The Love Philtre of Ikey Schoenstein."

His health was not robust, and confinement in a drug store did not improve it. A friend who was going to Texas invited him to go along, and from 1882 to 1884 he lived on a ranch, acting as cowboy, and at odd moments studying French, German and Spanish. Then he went to Austin, where at various times he was clerk, editor, bookkeeper, draftsman, bank teller, actor and cartoonist. In 1887 he married Miss Athol Roach. He began contributing short stories and humorous sketches to newspapers, and finally purchased a paper of his own, which he called Rolling Stones, a humorous weekly. After a year the paper failed, and the editor went to Houston to become a reporter on the Daily Post. A year later, it was discovered that there were serious irregularities in the bank in which he had worked in Austin. Several arrests were made, and O. Henry was called to stand trial with others. He had not been guilty of wrong doing, but the affairs of the bank had been so loosely managed that he was afraid that he would be convicted, so he fled to Central America. After a year there, he heard that his wife's health was failing, and returned to Austin to give himself up. He was found guilty, and sentenced to five years in the Ohio penitentiary. His wife died before the trial. His time in prison was shortened by good behavior to a little more than three years, ending in 1901. He wrote a number of stories during this time, sending them to friends who in turn mailed them to publishers. The editor of Ainslie's Magazine had printed several of them and in 1902 he wrote to O. Henry urging him to come to New York, and offering him a hundred dollars apiece for a dozen stories. He came, and from that time made New York his home, becoming very fond of Little Old-Bagdad-on-the-Subway as he called it.

He had found the work which he wished to do, and he turned out stories very rapidly. These were first published in newspapers and magazines, then collected in book form. The first of these volumes, Cabbages and Kings, had Central America as its setting. He said that while there he had knocked around chiefly with refugees and consuls. The Four Million was a group of stories of New York; it contained some of his best tales, such as "The Gift of the Magi," and "An Unfinished Story." The Trimmed Lamp and The Voice of the City also dealt with New York. The Gentle Grafter was a collection of stories about confidence men and "crooks." The material for these narratives he had gathered from his companions in his prison days. Heart of the West reflects his days on a Texas ranch. Other books, more or less miscellaneous in their locality, are Roads of Destiny, Options, Strictly Business, Whirligigs; and Sixes and Sevens. He died in New York, June 5, 1910. After his death a volume containing some of his earliest work was published under the title Rolling Stones.

His choice of subjects is thus indicated in the preface to The Four Million:

"Not very long ago some one invented the assertion that there were only 'Four Hundred' people in New York who were really worth noticing. But a wiser man has arisen—the census taker—and his larger estimate of human interest has been preferred in marking out the field of these little stories of the 'Four Million.'"

It was the common man,—the clerk, the bartender, the policeman, the waiter, the tramp, that O. Henry chose for his characters. He loved to talk to chance acquaintances on park benches or in cheap lodging houses, to see life from their point of view. His stories are often of the picaresque type; a name given to a kind of story in which the hero is an adventurer, sometimes a rogue. He sees the common humanity, and the redeeming traits even in these. His plots usually have a turn of surprise at the end; sometimes the very last sentence suddenly illuminates the whole story. His style is quick, nervous, often slangy; he is wonderfully dextrous in hitting just the right word or phrase. His descriptions are notable for telling much in a few words. He has almost established a definite type of short story writing, and in many of the stories now written one may clearly see the influence of O. Henry.