A tax obligation is incurred. An inventory item is lost or stolen. A tax refund is received. A product is manufactured or assembled from raw materials. The local price of real estate changes.
Market prices change.
There are many others. See the fictional business called Joe's Old Shoe Shop that is an example of this process. Since accounting consists of keeping track of financial transactions, this is done by categorizing these transactions. For example some involve cash or bank accounts. Some involve inventory or other asset values.