While everything is, technically, an experience of some sort, there is something special to many experiences that make them worth discussing. In particular, the elements that contribute to superior experiences are knowable and reproducible, which makes them designable. The concept to grasp is that all experiences are important and that we can learn from them whether they are traditional, physical, offline experiences or whether they are digital, online, or other technological experiences. In fact, we know a great deal about experiences and their creation through these other, established disciplines that can—and must—be used to develop new solutions. These aren't always obvious and, surely, they aren't fool-proof, but it's important to realize that great experiences can be deliberate and based upon some principles that have been proven.
One of the most important ways to define an experience is to search its boundaries. While many experiences are ongoing, sometimes even indefinitely, most have edges that define their start, middle, and end. Much like a story (a special and important type of experience), these boundaries help us differentiate meaning, pacing, and completion. Whether it is due to attention span, energy, or emotion, most people cannot continue an experience indefinitely; they will grow tired, confused, or distracted if an experience, however consistent, doesn't conclude.
At the very least, think of an experience as requiring an attraction, an engagement, and a conclusion. The attraction is necessary to initiate the experience, though this need not be synonymous with distraction. An attraction can be cognitive, visual, auditory, or it can signal any of our senses. For example, the attraction to fill-out your taxes is based on need and not a flashy introduction. However, there still needs to be cues as to where and how to begin the experience.
The engagement is the experience itself. It needs to be sufficiently different than the surrounding environment of the experience to hold the attention of the experiences as well as cognitively important or relevant enough for someone to continue the experience.
The conclusion can come in many ways, but it must provide some sort of resolution, whether through meaning or story or context or activity to make an otherwise enjoyable experience satisfactory. Often an experience that is engaging has no real end, leaving participants dissatisfied or even confused about the experience, emotions, or ideas, they just felt.
Most technological experiences—including digital and, especially, online experiences—have paled in comparison to real-world experiences and they have been relatively unsuccessful as a result. What these solutions require is developers that understand what makes a good experience first, and then to translate these principles, as well as possible, into the desired medium without the technology dictating the form of the experience.