Can anybody explain the theory of relativity an with example?

This is the basic theory of relativity and then a brief
explanation of Einstein's special relativity.  Basic relativity (Galileo and Newton)
states that the laws of physics are the same for all things moving in uniform motion. 
That is, everything is moving; there is no privileged or absolute "at rest."  So, there
is no "One" best place from which to observe things
happening.

Everything is moving; you are on Earth, which
spins on its axis and revolves around the Sun, yet, standing still, you think you are at
rest.  You're not.  Everything moves relative to everything
else.

Imagine you are standing on a street.  A car is
coming at you at 50 mph.  The driver of the car sees you coming at him at 50 mph.  Who
is right?  Both of you. 

Imagine you are standing on the
shore. You watch someone on a boat drop a ball on deck.  From the boatsman's point of
view, the ball drops straight down.  From your point of view, on the shore (at "rest"),
you see the ball drop not straight down, but on a slant to the east because the boat is
traveling east.  You're and the boatsman's perceptions of the path of the ball are
different because you have different frames of reference. Neither of you has a
privileged reference point (no absolute state of rest), so you are both justified in how
you see the ball. 

Now, imagine an airplane is struck by
lightning at the front and back.  From your position on land (again, seemingly at rest),
you see the two bolts strike simultaneously.  But for a person seated in the middle of
the plane, and although it is a difference of fractions of a second, she sees the front
bolt first because she is moving towards that bolt and she is moving away from the bolt
hitting the tail of the airplane.  Classic relativity tells us that the bolts occur
simultaneously because time is absolute; she (on the plane) sees the front bolt first
because it has less distance to travel to her eyes - because she is moving towards it
and away from the rear bolt. Makes sense,
right?

Transition:

Einstein
thought the speed of light is constant.  That is, it travels the same speed relative to
anything no matter what speed or direction that thing is traveling. So,
the light from bothbolts travels at 186,282 mps towards the middle of the
airplane regardless of the airplane's movement; even though you'd think the light from
the front would have to travel faster or go a shorter distance.

Since the light from the two bolts is is
the same speed and since both bolts travel the same distance to the middle of the
airplane, what is the remaining variable?  It's not distance and not speed that is
relative here, so it's TIME.  Here is where Einstein showed time to be relative! For the
person moving, in the plane, she observes the front bolt - Not because it is moving
faster and Not because it has less distance to travel.  She sees it first because it
takes less time for the front bolt to get to her.  Why?  Same distance, same speed. 
Time slows down as you approach the speed of light. The faster you move, the slower time
becomes - only noticeable at near light speeds. 

Common
sense tells you that you'll experience the event you're moving toward because it has
less distance to get to you. Your observation is relative to your motion.  This is
classic relativity.

Special relativity states that time is
also relative to your motion. Since light moves at the same speed, regardless of speed
or direction, it is time that changes!