Choosing the right Marketing Objective is important when setting up an optimal Campaign structure in your Ads Manager. You are providing Facebook with valuable guidelines by letting them know what your end goal is. Basically, what objective you choose depend on the end goal of your Campaign. Having an optimal Campaign structure in place makes it easier for both Facebooks and our algorithms to understand what you want to achieve with you Campaign.
To optimise your Campaign in the best possible way you need to give Facebook your end goal. Providing Facebook with your end goal is actually the first step you take when setting up a Campaign. It's called Marketing Objective.
There are three different main Objective categories Awareness, Consideration and Conversions. Within these three main categories are different types of objectives:
- Awareness contains hosts objectives that will help generate interest in your product or service.
- Consideration contains objectives that will get people to think about your product or service.
- Conversion contains objectives that will make people interested in your business take action. Such as buy your product or use your service.

For an easy guideline you can see it as See, Think, Do. It's also a good idea to create your Ad copy and Creatives with that structure in mind.
Let me give you an example of what objective to use and when:
Okey, first example; Lets say we're an e-commerce and we want to drive potential customers to our store with the intent to purchase. Then choosing the Traffic Objective might not be such a good idea, because you're then telling Facebook that your main goal with the campaign is to drive traffic and not purchases. So go for a Conversion Objective such as Conversions to reach those with potential higher purchase intent.
You can also choose to use the Catalogue Objective for this purpose but you then need to have a Catalogue with products connected to your account. It is also possible to drive offline visitors to your physical store. This is also under the Conversions umbrella.
(But again, if your Traffic Campaign is converting really well, there is no need to change a winning concept. What you could do in that case is to add a Conversions Campaign to your structure to pick some high intent customers.)
In the second example; Lets say we have an App and we want to get more App Installs – we then simply select the App Install Objective. On Ad Set level you can later select which App Store to send them towards to make the actual download;

To sum it up; By providing Facebook with your Marketing Objective you are making it way easier for Facebooks Algorithms to understand what you want to achieve with the Campaign in question.