Consider a typical app..once the "page loads" the display does not change until it is manually "refreshed". It is dead, lifeless. The apps we develop have auto-updating UIs that do not need to be "refreshed".
If Bob performs an action, e.g. adding/updating/deleting a record, Sue can be informed of Bob's actions automatically and immediately.
We use a style of programming that treats the values in an app like the values in a spreadsheet (changing one value can trigger changes to other values). This style of programming, when coupled with real-time features, breathes life into otherwise static/lifeless apps. These types of systems are notoriously difficult to control. We've arrived at solutions that can be used to gain mastery over "reactivity" in any scenario.
..with decades of experience across many languages and technologies