Every physical quantity we measure in the real world is a continuous quantity. For example , the temperature increases continuously with out a jump at any point abruptly. When we fill a glass, the volume or the height of water in the glass increases continuously and gradually,
Discrete data exists only as one of some predefined values.
Like marks awarded - it is only an integral number. classes or sections in a school. In the digital computer world. computer understands only 0 and 1. only two discrete values.
The real world is full of continuous data. Computer programs works on discrete data. A street is a continuous entity. But house numbers are discrete.