To help you find the things you're looking for, you can use labels.
To use them, you'll need to set them up yourself beforehand, and it's a child's game to do so! Let's look into where you can use them, and how you can improve your everyday life with them! 

Before anything, let's talk about what your labels can and cannot be:

In each part of the Campaign Creation Flow, you can toggle the display of the labels on or off: 

Any search for a label should be preceded by a Hashtag (#). It will look like this: #label1.

It is combinable with other words, meaning you can type #label1, add a space and then type another word on its own - this will look for anything with the label #label1, and containing the word you chose in their title. 

You can also search for multiple labels at the same time, simply adding a space between each: try #label1 #label2 for instance. It will look for any item that has both labels at the same time!

You can find labels inside of each step of the Creation Flow. 

Labels for audiences are useful especially for Saved Audiences. You can add them while creating them: 

Simply click on them and they will be added to your saved audience!
You can then look into your Audience Library and you'll see your labels under each saved audience: 

If you want to search for an audience with a specific label, input in the search bar the label you're looking for. 

You can also add a word following the label (after putting a space), and it will look for Audiences with the label mentioned and that contain the word you chose in their title!

You can also add a label to a saved list of interests to make sure you'll find them quickly next time! 

You can also use labels in the Creatives step, for existing posts in your timeline: 

Once you've labeled a creative, you can find them using the search function at the top of the page:

Using this feature you can find any creative using the label(s) you want!

You can also select several posts in your timeline and choose to edit all of the labels at the same time!

You can choose to add a label to any image or video you choose to upload while creating a new ad!

You can add a label to a Twitter Card, to find them quicker next time as well - the principle is exactly the same as the one for any other Creative. 

You can also leverage your labels directly from the axes!
Simply use them as filters for your Creatives: