What is the subject matter & plot of Waiting for Godot?

In Waiting for Godot, Vladimir and Estragon discuss how
they are waiting for someone named Godot who never arrives. They know that they should
wait by the tree, but are not entirely sure if they have the right tree. Time is
presented surreally in the play, with a sense that the scene of waiting is repeated
infintely in a worlld in which time and place are constructed in the minds of the
characters rather than as external objective realities. The characters do not really
know who Godot is and might not recognize Godot if they see him. A boy is used as a
messenger to inform the characters that Godot will not appear "today" but may appear
"tomorrow."

Two other characters, the master Pozzo and the
slave Lucky, enter in the second act and are initially mistaken for Godot. Although
Pozzo is in theory the master, he (in a parody of Hegel) is increasingly shown to be
dependent on his slave Lucky.

Godot symbolizes the God of
Messianic religion, who is expected at some time in the futuire as the salvation of the
characters, but never actually arrives. Lucky, as a thinker, attempts metaphysical
knowledge of God, but his speech fades to nonsense. Vladimir and Estragonwait by the
tree (the tree of the Gareden of Eden which is typologically the cross) and discuss
religious and other themes, but don't actually understand what they are waiting for or
why. Like many of Beckett's plays, this is a deeply pessimistic portrait of the futility
of human existence, and the failure of Messianic religion to save humanity from an
absurd and indifferent universe.