O Henry's use of irony is also prominent. Irony can be seen not just in the endings but also throughout the stories. He might set up a situation where a character thinks they are in control or about to achieve something great, but then circumstances work against them in an ironic way, highlighting the unpredictability of life.
His stories often focus on ordinary people in urban settings. He portrays the struggles, hopes, and dreams of the common man. These characters are very relatable, like the clerks, waitresses, and small - time crooks that populate his stories. This makes his stories accessible and engaging to a wide audience.