What is case?
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
Is there a case system in English?
it has largely lost its case system
Does Esperanto have an extensive case system?
yes
Between languages does the number of cases stay the same?
no
How many does German and Icelandic have?
four
What about Turkish, Latin and Russian?
they each have at least six
What about Tsez?
sixty-four
What are forms such as me, him and us used for?
the object
What about I, he, and we?
they  are used for the subject
How many cases do personal pronouns still have in English?
three