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In this video, we're going to move on to our next big subject, which is type annotations and type

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inference.

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These are technically two different systems inside of TypeScript, but we're going to talk about them

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in parallel for a very good reason, just to make things a little bit more complicated as well.

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These two different features apply slightly differently to variable declarations, functions and objects.

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So we're going to first talk about type annotations and inference as applied to variables.

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And we'll take a break and talk about them applied to functions and then objects and so on.

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For each of these different subjects, we're going to once again through go through some plain definition

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and overview.

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Well, then take a look at some different code examples that we're going to write out together.

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You'll notice I swap these two steps right here this time around.

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So we'll then talk about why we care about this annotation and infant stuff and we'll discuss when to

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use it.

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So let's get to it.

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First off, some plane definitions, so type annotations, what is that a type annotation is some tiny

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bit of code that you and I are going to write to tell typescript what type of value a variable refers

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to.

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All right, now, before expanding on that definition, let's talk about what type inferences, so it's

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type inference, TypeScript, is going to attempt to automatically figure out what type of value a variable

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refers to.

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And you'll notice that the kind of definition of both these are very similar in both cases.

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It's what type of valuable, what type of value, a variable.

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What will it refer to?

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So the interesting thing about type annotations and type of inference is that they're kind of at odds

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with each other.

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In one case, you and I are adding in a little bit of code to tell TypeScript what different types we

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are working with, with type inference.

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We are relying upon TypeScript to do that work for us.

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So these two features are a question of are you and I are going to do everything manually or are we

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going to leave it up to TypeScript?

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That's what the big question here is.

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And that's why what is going to be the big focus of our discussion about, you know, why we care about

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these features and when to use them?

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Let's take a quick pause right here.

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We're going to come back to the next video and start taking a look at a couple of different code samples.

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So quick pause and I'll see you in just a minute.