Case is a special grammatical category of a noun, pronoun, adjective, participle or numeral whose value reflects the grammatical function performed by that word in a phrase, clause, or sentence. In some languages, nouns, pronouns, adjectives, determiners, participles, prepositions, numerals, articles and their modifiers take different inflected forms depending on what case they are in. As a language evolves, cases can merge (for instance, in Ancient Greek, the locative case merged with the dative), a phenomenon formally called syncretism. 

English has largely lost its case system, although personal pronouns still have three cases that are simplified forms of the nominative, accusative and genitive cases: subjective case (I, you, he, she, it, we, they, who, whoever), objective case (me, you, him, her, it, us, them, whom, whomever) and possessive case (my, mine; your, yours; his; her, hers; its; our, ours; their, theirs; whose; whosever). Forms such as "I", "he" and "we" are used for the subject ("I kicked the ball"), whereas forms such as "me", "him" and "us" are used for the object ("John kicked me"). 

Languages such as Sanskrit, Ancient Greek, Latin, Armenian, Hungarian, Tibetan, Czech, Slovak, Turkish, Tamil, Romanian, Russian, Polish, Serbo-Croatian, Estonian, Finnish, Icelandic, Ukrainian, Lithuanian, Basque, Esperanto and the majority of Caucasian languages have extensive case systems, with nouns, pronouns, adjectives, and determiners all inflecting (usually by means of different suffixes) to indicate their case. The number of cases differs between languages: German and Icelandic have four; Turkish, Latin and Russian each have at least six; Armenian, Czech, Polish, Serbian, Croatian, Ukrainian, and Lithuanian have seven; Sanskrit has eight; Estonian and Finnish have fifteen, Hungarian has eighteen and Tsez has sixty-four.
What is case? Is there a case system in English? Does Esperanto have an extensive case system? Between languages does the number of cases stay the same? How many does German and Icelandic have? What about Turkish, Latin and Russian? What about Tsez? What are forms such as me, him and us used for? What about I, he, and we? How many cases do personal pronouns still have in English?
a special grammatical category of a noun, pronoun, adjective, participle or numeral whose value reflects the grammatical function performed by that word in a phrase, clause, or sentence. In some languages, nouns, pronouns, adjectives, determiners, participles, prepositions, numerals, articles and their modifiers take different inflected forms depending on what case they are in it has largely lost its case system yes no four they each have at least six sixty-four the object they  are used for the subject three