Answer:
Conditional formatting.
Step-by-step explanation:
Conditional formatting is the technique used in excel to highlight certain cells for the purpose of reference or for indicating any kind of error. These cells are formatted based on certain conditions which on getting accomplished highlights the cells with the respective colors assigned for that particular condition. For example, the cells are formatted to highlight the color with red if any value (say, marks of students) is found below 40. Thus, on receiving a value less than 40, the cell would automatically be highlighted with red color.