This provides an easy way to clear data related to products, orders or sessions. For each type of deletion, the system knows which tables should be cleared.
Where possible, avoid clearing individual tables directly in the database unless you're absolutely sure you understand the consequences. There are some tables in Kartris (such as config settings and language strings) that should always have data, even in a new install that has no products or customer records.
Deleting data from some tables without understanding the relationships can also leave orphan records behind. For example, version records always link to a parent product. If you delete all data from the products table only, you would end up with many orphan records from versions, language elements (the language specific content of products like descriptions and names), related products, etc.