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In this lecture, we're going to briefly discuss two terms that you'll hear often.

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I mentioned them a lot in the past few lectures.

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I'm talking about references and snapshots.

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I frequently get asked by students what the differences are because they seem similar.

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Let's talk about them independently.

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Starting with references.

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A reference is an object pointing to a location in your application.

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So far, we've learned we can create references to either the database or storage by pointing to a location

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in the application, we can perform operations such as reading and writing to that location.

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We use references to upload a file to the storage and add data to the database.

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References can create other references.

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This behavior allows you to manage multiple locations.

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Next, let's talk about snapshots.

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Snapshots are objects that are a copy of a location in your application.

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They're read only and are immutable.

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Immutable means they can't be updated.

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If you were to attempt to update a snapshot, those changes wouldn't be reflected in Firebase.

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Whenever we make a change to the application, it's typical for Firebase to respond with a snapshot.

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One example of a snapshot was when we initiated the upload to Firebase.

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We were constantly fed snapshots of the upload process.

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In summary, references and snapshots allow you to read the data in Firebase.

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References can be used to manipulate the data in your application.

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However, snapshots are read only objects.

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This makes them memory efficient.

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It's the primary reasons why Firebase has snapshots.

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You don't always want to interact with Firebase snapshots make your application more lightweight.

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As a result, this makes your application run faster.

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One last point I want to make is that snapshots are usually returned whenever you listen to changes

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using a reference.

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You can't create a snapshot directly.

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It's created for you during events.

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Hopefully, this makes things a little clearer when reading the documentation.

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You'll find both words thrown around a lot.

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Knowing the difference will make development easier.