Ais an effort or strategy to achieve a goal or a solution to a problem that is not readily apparent.

Concept.

Explanation:

Concept is usually defined by grouping that occurs in our mind, and this way, we are putting similar things, events and people to a group.

It is used in order to remember and understand what things represent, what they are, what their meaning is and which category they belong to.

Example:

If someone says '' I think of a cake '' the concept '' cake '' will trigger some ideas in one's head like what the concept represents and what kinds of characteristics it posses -- does it have topping or cherry on top, is it round or is it big or small, is it pink, red, colorful, is it tasty or not etc.