The term user experience contains all aspects of user interaction with the final product, support services and all other people who participated in the design and development process. This means that everybody who contributed in any phase of creation, support, and product improvement process are user experience designers in a way.
A user experience designer could be the interface designer who creates screens and design elements, a frontend developer who implements the design over different devices and resolutions, a backend developer who developed an optimized algorithm to load data from a database, a customer support service that is helpful and cordial, marketing staff that communicates clearly to users what the product does and what the benefits of using it are, etc.
What we as end users see on the screen is just an interface design and only a part of the overall experience. The term "user experience" encompasses all aspects of user interactions and user interface is just a part of it. Perception of good user experience is established and maintained by individual subjective perception, adaptability to end user and is a combination of user adopted attitudes, fluctuating emotions, and preset expectations. The first expectation of the product or service is that it works well and meets the exact needs of the end user, after that comes usability aspects such as ease of use, attractiveness, user friendliness, efficiency etc.
But what about lacking customer support, infinite server load time, upgraded operating system incompatibilities, or marketing the product without a clear vision? Are all of these multiple disciplines also part of the user experience? The answer is yes, the end user is subjective and focused on the task at hand and one or two bad traits previously mentioned can break a good user experience regardless of other great features.
“It’s really hard to design products by focus groups. A lot of times, people don’t know what they want until you show it to them.” - Steve Jobs
Great user experience is like making a dish with all different parts, services, and features working together. For example, if the load time from the server is slow it's, in layman's terms, a salty dish. One really bad feature can break a good user experience and anything that was done right can easily be forgotten. In a way, we are spoiled to expect only the best because most of the time we use products that are made by the greatest experts, created over long periods of time and are continually improved. We are conditioned to get things we want easily because competition for customers is high and everybody wants to sell their products. Everything is within a hand's reach, which can also be part of a good experience. It's not a bad thing and doesn't mean that your product is doomed to failure but it shows different all-encompassing perspective to creating a satisfying user experience.
A lot of features and services can be reused, optimized and adjusted so they are good enough initially and work well together in harmony hence achieving good user experience. Thoughtfulness of user needs and attention to details is a practical approach that guarantees good user experience that can evolve incrementally into a great experience like with all other great products that we use today.
“Your old site is the best prototype of your new site.“ – Hoa Loranger
To summarize everything - a good user experience is created, a great user experience is a never-ending process, and bad user experience is the result of one or two slip-ups in the overall product development process.