Later, we will start implementing the collecting system, but first we need to distinguish the Player from other objects. One way to do it is to assign a Tag. When you install Unity, it comes preloaded with a set of default tags. However, if you want to add your own (custom) tags, you can do it by navigating to Edit | Project Settings | Tags and Layers, like in the following menu:

In our specific case, we can select the Player, and just beneath the name we can set Player as a tag, which is a default tag, as shown in the following screenshot: