The change of word form according to grammatical function, which occurs in inflected languages.
Inflection is differentiated depending on the class:
Words often do not appear in a fundamental form (the word root) except in dictionaries and grammars.
A schema of all inflections for a word is sometimes called a paradigm.
Various major languages, including English, German, Russian, Spanish, French, and Hindi - all Indo-European languages - are inflected to a greater or lesser extent.
The most obvious inflections in English occur in strong verbs, e.g. I am, you are and to take, I took; and nouns, one man, all men; foot, feet. Weak inflections, however, are more common, such as I love, I loved, he loves; John, John's car.