CSAT stands for customer satisfaction and is used to measure and quantify how customers feel after they have gone through a specific customer journey. This can be with a product or an experience.
In most cases, CSAT can be measured with a score. Different organizations use different forms of scores, from ratings to emojis. Measurable CSAT can be based on things like interaction, support, ease of purchase, resolution, conversation, customer service, onboarding, etc.
While it is not a required step in any customer journey, it is important to measure customer satisfaction if you are to identify areas that are likely causing churn. If you are not measuring customer satisfaction, you are less likely to be able to resolve customer issues.
The main goal of collecting customer satisfaction is to be able to increase retention which impacts all areas of your business. Higher retention equals more customer loyalty, which in turn means larger customer acquisition.