What is an interaction between two or more organisms in which one species lives on or in another?

An interaction where one species lives on or in another is known as parasitism. In this relationship, the parasite benefits by obtaining nutrients or shelter, often to the detriment of the host organism, which may experience harm or disease. Common examples include ticks feeding on mammals or tapeworms residing in the intestines of their hosts. This interaction can significantly impact the health and survival of the host species.