> Graphical user interfaces traditionally use retained mode-style API design,[2][5] but immediate mode GUIs instead use an immediate mode-style API design, in which user code directly specifies the GUI elements to draw in the user input loop. For example, rather than having a CreateButton() function that a user would call once to instantiate a button, an immediate-mode GUI API may have a DoButton() function which should be called whenever the button should be on screen.[6][5] The technique was developed by Casey Muratori in 2002.[6][5] Prominent implementations include Omar Cornut's Dear ImGui[7] in C++, Nic Barker's Clay[8][9] in C and Micha Mettke's Nuklear[10] in C.

https://en.wikipedia.org/wiki/Immediate_mode_(computer_graph...

[Edit: I'll add an update to the post to note that Casey Muratori simply “coined the term” but that it predates his video.]