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In the previous sections,

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we learned about data fetching

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and we learned about data mutations.

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And what you already saw there,

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at least in certain situations,

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was that data may sometimes not update,

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or the pages that display the data may sometimes not update

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as expected because NextJS does some caching for you.

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And that's exactly

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what we'll take a closer look at in this course section

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because in this section we'll analyze how exactly

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NextJS caches data and pages,

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and what that means for you.

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You will learn how you can get NextJS

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to revalidate cached data

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and throw away cached data

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so that updated data is displayed when needed.

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And we'll also take a look at

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how you can control which data is being cached

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depending on which data source you are using.