Delta is the symbol that you use for "Change of" in maths. (its that sort of triangle thing)) So for example delta distance traveled over delta time, is speed (velocity) ie MPH.
When people use it in computing terms, they mean "Something that happens over time/ The time change"
So if you have (say), a sprite moving accross the screen, it could move one pixel a second, or one pixel a frame. The delta time being a second or a frame respectivly.
Now if something goes wrong with your game logic, (Or whatever), and it spends too much time doing somthing, you might "miss" a frame.
You now have the choose of just draw the frame that I missed, or you could find out how late it is, and draw the correct frame.
Imagine a sprite needs to go from the left to the right of the screen in one second. The change in time (Delta time) is one second. The change in position is Screen width. When you come to draw the frame, you find out how much of the second has passed. And draw the sprite at that percentage of the ditance accross the screen.
When people use it in computing terms, they mean "Something that happens over time/ The time change"
So if you have (say), a sprite moving accross the screen, it could move one pixel a second, or one pixel a frame. The delta time being a second or a frame respectivly.
Now if something goes wrong with your game logic, (Or whatever), and it spends too much time doing somthing, you might "miss" a frame.
You now have the choose of just draw the frame that I missed, or you could find out how late it is, and draw the correct frame.
Imagine a sprite needs to go from the left to the right of the screen in one second. The change in time (Delta time) is one second. The change in position is Screen width. When you come to draw the frame, you find out how much of the second has passed. And draw the sprite at that percentage of the ditance accross the screen.