An inflecting language uses affixes (inflections) to conjugate verbs, decline nouns and other tasks.
Some languages use suffixes for this purposes, while others use prefixes or even infixes.
In English for example -s is used for pluralizing names and -ed is used to form the past of regular verbs. Both are examples of suffixes.
The negative particle in- as in the words independent, insane, inaccurate, is an example of prefix, instead.
Another type of inflection is the change of the root form of a word. Examples are the inflections of the irregular verbs in English, like sing - sang - sung, which are inflected forms of the lexeme "sing".
In an inflecting language the form of nouns, adjectives, or pronouns, shows their grammatical relationship to other words.
Languages such as Russian or Latin have complex inflectional systems.
English in comparison does not rely so heavily on inflection but word endings are used to mark grammatical categories as noun case and verb tense, for example.