Diminutives are often employed as nicknames and pet names when speaking to small children and when expressing extreme tenderness and intimacy to an adult.
[1] For example, in Spanish gordo can be a nickname for someone who is overweight, and by adding an -ito suffix, it becomes gordito which is more affectionate.
In English, the alteration of meaning is often conveyed through clipping, making the words shorter and more colloquial.
Diminutives formed by adding affixes in other languages are often longer and (as colloquial) not necessarily understood.
While many languages apply a grammatical diminutive to nouns, a few – including Slovak, Dutch, Spanish, Romanian, Latin, Polish, Bulgarian, Czech, Russian and Estonian – also use it for adjectives (in Polish: słodki → słodziutki → słodziuteńki) and even other parts of speech (Ukrainian спати → спатки → спатоньки — to sleep or Slovak spať → spinkať → spinuškať — to sleep, bežať → bežkať — to run).