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Think about the web applications
you interact with on a daily basis.

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We use applications for huge variety
of things, but at their simplest,

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many follow a common pattern,
create, read, update and delete.

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Take a blog or
a popular social media site, for example.

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You can usually make a new post,
that's create, view other posts,

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that's read, edit a post, that's update,
or delete a post, that's delete.

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This pattern is commonly known by
the acronym CRUD, create, read, update and

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delete.

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REST APIs allow a client to manipulate
data using actions that map closely to

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the idea of CRUD.

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These actions are get,
post, put and delete.

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Get, post, put, and delete are known
as HTTP verbs or HTTP methods.

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There are actually many more HTTP methods,
but

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we'll concentrate on these four because
they're the most commonly used.

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See the teacher's notes if you want to
learn more about HTTP protocol, but

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basically it's an agreed upon standard for
communication over the Internet.

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Information in a REST API is typically
organized using nouns that describe

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what the data represents, nouns like
users, posts, movies, or recipes.

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Using HTTP methods and API nouns, a client
can tell a REST API what information

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it wants and
what it wants to do with that information.

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As an example, If the client sends
a get request to the resource/movies,

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it means it expects to read or view data
representing a collection of movies.

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A post request means it
wants to create a new movie.

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Put means it wants to update
an existing movie, and

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delete means it wants to,
you got it, delete a movie.

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When we write an API,

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we're essentially programming responses
to various HTTP requests for resources.

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Through code,
we say to our express application,

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when a client makes a get
request to the resource/movies,

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respond with a JSON object
containing a list of movies.

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At the core,
that's really all an express API does.

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It takes in requests, and
responds with JSON objects.

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I've just thrown a lot at you that may
seem unfamiliar, but stick with it.

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In the next video,

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we'll build a simplified example of
how this all comes together in code.

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Are you ready?