Quite often Designers are asked what is the best feature that an XD solution can have and in my opinion, the level of success of a project is measure by the engagement of the user. Engagement is one of the design criteria that build an Experience Design concept, it is responsible for keeping the user on the page and make them wanting more.
Some things we need to consider when building engagement is judging whether the solution presented is accessible, usable, credible, learnable, and desirable to the user. We must constantly ask all these questions during the development and design of the concept.
Some things we need to consider when building engagement is judging whether the solution presented is accessible, usable, credible, learnable, and desirable to the user. We must constantly ask all these questions during the development and design of the concept.

The Shape of Engagement: The Art of Building Enduring Connections with Your Customers, Employees and Communities | Available at Amazon
A book called “The Shape of Engagement: The Art of Building Enduring Connections with Your Customers, Employees and Communities” by Scott Gould explain in depth what makes people engage with different things. Scott is an expert on how people engage with ideas, brands, organisations, and each other.
“Eight years in the making, and drawing on almost two decades of experience, Scott will reveal to you:
1. What makes engaging companies outperform their unengaging counterparts by 29.9% increase in stock price year on year
2. What's getting in the way of your engagement succeeding, and why trying to "get" people to engage doesn't work
3. Why a click is NOT engagement, and what the difference is between participation, connection, and interaction
4. What the three types of engagement are, and how to tell if they are at work in your organisation
5. What the six psychological steps of engagement are, and what strategies to use at each stage
6.What truly motivates people to engage
7.How to operationalise engagement within an enterprise”
1. What makes engaging companies outperform their unengaging counterparts by 29.9% increase in stock price year on year
2. What's getting in the way of your engagement succeeding, and why trying to "get" people to engage doesn't work
3. Why a click is NOT engagement, and what the difference is between participation, connection, and interaction
4. What the three types of engagement are, and how to tell if they are at work in your organisation
5. What the six psychological steps of engagement are, and what strategies to use at each stage
6.What truly motivates people to engage
7.How to operationalise engagement within an enterprise”
In an Interview for the UX Planet Website, Scott mentioned that User Engagement has become a buzzword and that is not only the number of clicks, or taps, or downloads of an app but also the psychological state that is happening within.

Scott Gould | image source
In other words, its became a science for us, as designers, to understand users' psyche and find out what their intrinsic needs are. Once we understand that and have the methodology to translate these into a physical design, that’s our formula!
But how do we measure engagement? There are two ways to do it through behavior, first is to use a series of operational KPIs, such as DAU, churn rate, ARPU, or MAU. These will provide one-dimensional measurements.
Secondly, the more insightful way to measure engagement is to consider the 6 psychological levels of engagement:
Secondly, the more insightful way to measure engagement is to consider the 6 psychological levels of engagement:
Acknowledge: Users are mentally aware of you. Based on visits to your website, people on a mailing list, or followers on social media, etc.
Explore: Users are discovering more about you. This might be longer visits on a website, interaction with content on social, or even downloading an app and testing it.
Act: f you users haven’t signed up to your product yet, they definitely have by now, but you have not yet passed the “home screen” test. Typical measurements revolve around a core action.
Identify: The user identifies with the product. Measurements are often based on a degree of usage that indicates emotional connection.
Integrate: Having identified with the product, the user commits to it and makes it a part of their daily life.
Enlist: The user adopts the same end goal as you and subscribes to your mission. This could be measured with contributive KPIs.
At the end of the day, we just know that at an intuitive level, if something is engaging, it will have a greater chance of success. But where do we start? According to Scott, we must first connect on a mental level with users, designing brands, logos, slogans that exist to inspire. Secondly, we connect on a physical level, by adding cool illustrations, enriching the graphic design, make users tap and click, this is physical engagement. And Thirdly on an emotional level, where the user creates a bond with the solution, and this is done by adding different functions that can provide purpose, fulfilment and identity.