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Hi and welcome to this new section of
the course! And in this section starts the

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real deal, so in this section we're going
to develop the first application of

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the course. Until now you went through the
basics of Python. You learnt functions,

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loops, conditionals, and handling files etc.
Now we're going to practice all those

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concepts but actually building real
programs that can be used by users

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instead of just looping through trivial
strings and numbers and so . And so

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what are we going to build in this
section? Well are you going to build a

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program which you can give a word, an
English word and the program will return

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the definition of that word in English.
So let me go ahead and demonstrate the

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program. I'm using Python 3. App1.py is
the script. So the program asks you to enter

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a world which you want a definition for.
For instance let's say mountain. And so

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you get the definition for mountain and
in this case it happens to have two

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definitions. So mountain and mountain is
a feature of the earth�s surface that rises

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high above the base. And also mountain
has another meaning which is a great

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number of large amount of things not
placed in a pile. Anyway there are words who

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have only one meaning like mathematics I
hope. Yeah, so you get only one definition

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for mathematics, but also the program has
other features as well such as you know

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if you put rain with double n, so with an
extra n and press Enter the program

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instead of crashing, it displays a
message, it tells you: �Did you mean rain

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instead?� So it's quite an intelligent program
that guesses the world that the user may

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that guesses the world that the user may
had in mind, may have had in mind

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when typing the word. So enter Y if
yes if you meant rain, or N if no.

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Yeah, I meant rain. And you get the
definition for rain which happens to

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have two definitions. This is the first
one. This is the second one. The program

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also if you enter a very random word
that doesn't have any meaning like that

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you get the message �The word doesn't
exist. Please double check it.� Because you

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know the program cannot find a similar
word to this. It cannot find a word first

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and also it tries to find a similar word to
this one, but it doesn't because I don't

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think there's a match for this and so it
prints out this message and there's also

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other things like you know if you have
mix of letter cases there like

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uppercase R and A you still get the correct
input there. So that's a program. It has a

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command line interface which means you
are inputting, you're passing the input

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through the command line and you're
getting the input again from the command

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line, however later in next sections I'm
going to explain you web applications.

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How to create verifications with Python so
you then may get back here and actually

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create a web application using the code
that you'll be learning in this section

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so you can extend this program to make
it more user friendly with a

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web interface where the users can enter
the input through a web form, so from a web

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page and then press a button and then get
the output on the web page. However

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the code that you'll be learning in this
section is very important. It's core

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Python so it's, you're going to learn about
conditionals and loops so you're going

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to implement all those that you learned
in a previous section by developing this

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program. So I hope you like this and I
wish you success!

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See you in the next lecture!