IN and ON are two examples of a preposition. Both IN and ON are parts of the most commonly used prepositions in the English Language. However, the usage of these two prepositions can be confusing if you don't have adequate knowledge about them. IN is mostly used to describe the exact position of something. For example, the plates are in the kitchen. It can also be used to describe the contents of a container. This means it can be used to indicate the different constituents of a particular entity. For example, God is in heaven, watching over His creations. IN can also be used to describe when an event is taking place. For example, John is getting married in December. ON, on the other hand, is used to describe the position of an object on a surface. For example, The foods are already on the table. ON, can also be used together with the date. For example, the program has been scheduled to start on Friday.