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We're almost done with this module.

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Now let me show you two other important pieces of data you can put into your documents.

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You can use embedded documents and this is actually a core feature of mongodb and a core feature

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I'll come back to in my data schema and relations module in this course.

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Let's imagine this box is one document, embedded documents then simply means that you can have a field

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in your document like name

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but then this could be another document, so the value of the field could be another document and

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you can have multiple such documents and these documents can have other sub documents which can have

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other sub documents, so you can nest your documents all in one overarching document in one collection.

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So here we can have up to 100 levels of nesting in mongodb,

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this is a hard limit but you can have a lot of nesting

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and to be honest, you rarely need more than three or four levels and you always got another hard limit,

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the overall documents size has to be below 60 megabytes.

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That might sound small but since you only store text in there, you don't store files in mongodb

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for example, you would use your file storage for that, since it's only text, 16 megabytes is actually

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quite a lot,

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still these are arrays to keep in mind.

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So these are embedded documents, another kind of data you can store are arrays

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and this is not strictly linked to embedded documents, though it can also be documents,

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you can have arrays in this case of embedded documents but arrays can hold any data,

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this simply means that you have lists of data in a document.

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Now this is of course very theoretical here,

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so let me show you an example in the next lecture.