Too Long; Didn't Read
A great mobile app starts with UX followed by UI, both are essential for the success of the application. Usability testing and focus groups are often confused, although both terms have totally different goals. Design is based on the understanding of how users see the app, what they think about it and behave. Designers are not able to build a user-friendly app, and they would not be able to add elements. UX design does not come after the important stuff is done, it can make or break the product.