What is "The Last Leaf" about?

“The Last Leaf,” by O. Henry, is the story of two women
who live together in an apartment in Greenwich Village in New York around the turn of
the twentieth century.  It is a typical O. Henry story about love, loneliness, and
sacrifice.

Both women are artists, and one of them, Johnsy
(short for Joanna), catches pneumonia and is close to death. She decides that she will
give up her struggle to live when the last leaf falls off the vine outside her
window.

However, Mr Behrman, their neighbor that lives
below them, is also an artist and hears what she decides to do. He paints a picture of
the last leaf still hanging on the fine, and one cold, wet night he climbs up a ladder
and places his painting right outside the window so that when the two women open the
window every day, they think the last leaf is still clinging to the vine, refusing to
give up life.  This inspires Johnsy to keep on fighting her pneumonia and eventually she
gets better. One day they finally discover that the last leaf is actually a painting,
and the real leaf had fallen much earlier.  Also fallen was the artist who painted it,
since he was old and caught pneumonia the night he put the picture in front of their
window.