Why does Hamlet say "to be or not to be" and what does it mean in Hamlet?

I think it is entirely possible that Shakespeare wrote the
“To be or not to be” soliloquy as a separate piece expressing his own personal feelings
about life and death and then put it away in the bottom drawer, as writers will do,
until he found a convenient spot for it when he was writing his play
Hamlet. What is important in this soliloquy, and what explains its
great popularity, is the truths it tells about human existence, not what it reveals
about the character of the moody Prince. We have all personally experienced some of the
slings and arrows Hamlet complains about, just by being alive and having to deal with
people and struggle to keep a niche in the crowded, competitive world. And we have all
felt discouraged and wondered whether existence was really worth the
trouble.

If we haven’t experienced all the slings and
arrows personally, we have seen others suffering and have wondered why some people will
continue to cling to life when they get nothing out of it but hard work and suffering.
If we live in a city we commonly see people who are totally blind trying to find their
way by feeling the pavement with long white canes. We see men sleeping in doorways on
the cold concrete. We see men rummaging through dumpsters and trash receptacles trying
to gather a few cans and bottles they can sell for enough to live on for one more day.
We see all sorts of ugliness and deformity. We see old people hobbling along, hoping to
survive just a little bit longer, although they have nobody to care whether they live or
die.

Shakespeare itemizes some of the negative aspects of
human existence in this soliloquy. They deserve more attention than the worn-out
questions of what Hamlet is really thinking about or whether he is really contemplating
suicide. We have all personally experienced “the proud man’s contumely,” “the pangs of
despised love,” and “the insolence of office” (if only at the Department of Motor
Vehicles).

Charles Dickens’s novels offer excellent
examples of some of the “outrageous fortune” which Hamlet summarizes in just a few
lines. In his novel Bleak House, Dickens describes the effects of
“the law’s delay” in the interminable case of Jarndyce v Jarndyce, during which the
lawyers of his day, like a flock of vultures, picked the estate clean and left nothing
but the bare bones. In his novel Little Dorrit, Dickens illustrates
“the proud man’s contumely” and “the insolence of office” in his characters’ dealings
with the Circumlocution Office. In that great novel, his character Daniel Doyce, who has
been trying for years to patent an invention, is an example of “the spurns that patient
merit of th’ unworthy takes,” while both Little Dorrit, who loves Arthur Clennam, and
Arthur Clennam, who loves "Pet" Meagles, offer good examples of “the pangs of despised
love.”

Shakespeare was probably talking for himself when he
wrote those famous lines beginning with “To be, or not to be.” He had had a rough life
and knew—better than any spoiled prince--what it was like to have to struggle for
survival in a brutal city like London of the sixteenth century. How could he have
written them otherwise?