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PROFESSOR: Hi, have you found it
particularly difficult to find

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a specific item in your house?

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Let's say you're looking
for a pair of gloves,

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but you just can't find it, and
you spend your entire afternoon

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looking for it.

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Well, you've just
encountered the same problem

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that companies like
Google or Microsoft

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encounter every single day.

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And that's the
problem of search.

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Just like a house which stores
thousands of different items,

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Google stores 45 billion
index pages of information.

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If every page was
a sheet of paper

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and we stack them up real high,
we'll create a tower 600 times

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taller than Mount Everest.

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Well, how can Google
find my results

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so quickly when I
find it so difficult

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to find a pair of gloves?

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Well, searching
on Google is kind

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of like looking for
person in a big school.

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Let's say you're looking for
James in a row of classrooms.

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One of the easiest
method would be

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to go to every classroom nearest
to you until you find James.

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There's a better method
called binary search.

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Now, let's say the students
were arranged from a to z,

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one in each classroom.

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We would then go
to the middle room

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first and see if James is there.

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And if James isn't
there we will look

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at the first letter in the
name, and if the letter is

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before j, we head to the right,
if not, we head to the left.

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We would then approach
the middle room

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in the newly sectioned area.

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Eventually we will repeat the
process over and over again

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until we find James.

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Now, this is just like the first
method, but it's at a much,

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much faster rate.

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How much faster would that be?

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Well, that depends on the number
of students in the school.

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Let's say there are 500 students
and we're looking for one.

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It will take about 80
minutes in the first method,

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But one and a half minutes
with binary search.

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But let's say there are
1,000 students in the school.

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It would take 160 minutes
with the first method,

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but 1.6 minutes with
the second method.

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Now that's a whole
lot of difference.

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So a name is just a word.

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But Google searches a
combination of words,

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making it a little
bit more complicated.

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So just like how we
identified the first letter

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of each alphabet
of the name, Google

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identifies 200 unique factors
making your search terms

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faster.

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Well, if you recall, the
effectiveness of binary search

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depends on the
prearrangement of data.

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And that's why computer
scientists are actively

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looking for ways to sort,
manage, and eventually retrieve

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data faster and better.

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In the same way, the TV
remote goes near the TV,

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the shoes go to the shoe rack,
the coats go into the cupboard,

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and the winter gloves go
into the winter jacket.

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Aha, so that's
where my gloves are.