 In this video, we're going to explain collections in Blender. To do that, we're going to try and separate our scene into two groups, one for characters and one for background objects. Collections are similar to what you might call layers or groups in other software. Each collection in your scene can hold objects of any kind for the purposes of organization and or rendering. You can also have collections within collections for further organization. In fact, that's what's already being done as the scene collection acts as the parent collection for all collections in a scene as you can see here. Now to start us off, let's make a scene that makes sense for our purposes. What we want to do is separate our scene into character objects and background objects. I'm going to go ahead and scale this cube up until we're inside of it. This will be our environment or background. Then I'm going to add a new object, monkey. This monkey, also known as Suzanne, will act as our character. If you take a look at the Outliner, you can see that our monkey has already been added to our existing collection. Whenever you add objects in the 3D viewport, keep in mind that they will be added to whatever collection you have selected at the time. In case you can't see any objects in your Outliner, your collection may be collapsed down to a single line. This is done by clicking this arrow on the left of the collection name. Then we click this arrow again to expand it. For hotkey users, you can press the plus and minus keys on the number pad. So let's try and move our character into a character collection. Well for that, there are a few ways to do it. But one of the quickest ways is to simply select the object and right click for a context menu. Under this menu, you'll see the Move to Collection option. If you click that, you'll be presented with a few choices. If we choose Scene Collection, this will bring our monkey out of its current collection. This is not what we want, and the only existing collection we see in this list is the one the monkey is already in. What we want is the New Collection option. So let's go ahead and click that and name our new collection Character. Quick tip to confirm the name after typing, simply hit Enter twice. Now if you look at our Outliner, you can see that our monkey is in our character collection. For hotkey users, you can press M as in Move to bring the same Move to Collection menu for whatever object or objects you have selected. Another way you can add an object to a new collection is to create an empty collection first. To do this, simply right click any empty space in the Outliner and click New. This will create a new collection within the Scene Collection. If instead of empty space, you right click a collection name, it will create a new collection within the collection you right clicked. For hotkey users, you can simply hover over the Outliner and press C to create a new collection in the Scene Collection. And if you happen to have a collection already selected, your new collection will appear under the selected collection. Fun fact, you can create as many collections as you like. You can rename collections at any time by double clicking or control clicking their names in the Outliner. So let's go ahead and rename our new collection as BG or Background. We can then move our cube, which is our background object, to our background collection in the viewport with the same Move to Collection menu, or the M hotkey, and then selecting the now existing background collection from the menu. Or we can use the Outliner and simply left click drag the object to the background collection. Now that we have our character object and background object in their respective collections, you can check and uncheck each collection to toggle their visibility. This will turn them off during render as well for the view layer you have selected. To quickly show you how view layers work with collections, I will create a new view layer up here. As you can see, the checked or unchecked state of each collection is unique to each view layer. But what about our light and camera objects? Let's say we want to have these objects in both the background and character collections so that they are visible whenever we isolate either one. However, when we try to move our objects to more than one collection, it doesn't work. While it is possible to link objects to more than one collection using the Shift M hotkey, a preferable way is to use collections within collections. Let's take a look at how that might work. First thing I'm going to do is rename our collection to car slash BG, car being short for character. If we were to simply drag the character and BG collections into our car slash BG collection, we can now toggle all collections within our car slash BG collection off or on with one check mark. But also keep the light and camera objects on while toggling the other two. Functionally, this achieves the same thing as adding the light and camera objects to both character and background collections. As you can keep the main collection enabled while toggling off the subcollections you don't want to include. If you do happen to use Shift M to link objects to multiple collections however, it becomes a bit harder to keep track of, as there will be duplicates in your outliner even though they represent the same object. However, if you do link an object to multiple collections like this, just know that you can remove the object from a collection by right clicking it in the outliner and selecting Unlink. Now that we have all of our objects in their proper collections, I want to explain a quick tip for when collapsing and expanding your collections. In case your outliner ever gets too busy, collapsing your collections can be very helpful. What's especially great is you'll notice a few icons next to the collection names. These icons represent what type of objects exist within each collection. For example, right now our character collection has only one object, but if you collapse the car slash BG collection, you'll see that it contains two collections, two meshes, one light, and one camera. This is very helpful for seeing at a glance what objects are within each collection in case you need a reminder. Now let's say for whatever reason, I want to delete this car slash BG collection. Deleting a collection does not delete the objects within the collection. For example, if we select the car slash BG collection in our outliner and hit the delete key, the collection is deleted but the objects within the collection are moved outside of that collection. As a final tip, in the outliner, you can press the eyeball icon to toggle on and off viewport visibility. This will not affect your renders, but will allow you to hide objects and collections while you work. For similar options, you can click this drop down menu in the top right hand corner to enable selectability toggles and more. And that's it for our collection overview. Collections are very powerful and the foundation of object organization in Blender.