English Alphabet may be written in two cases:
Upper Case & Lower Case.
In Upper Case we write like this: A,B,C,.....,Z
while in Lower Case we write like this: a,b,c,......,z
Uppercase letters are used at the beginning of sentences and the beginnings of words in a title. Also, when written on its own, "I" is always in uppercase. Proper nouns are always written in uppercase too, i.e. Names of people, places, etc.
For example, "I saw John when he came to England. We went to see Big Ben"
An uppercase letter is a letter that is written or printed in its larger form, typically at the beginning of a sentence or for proper nouns. These letters are also known as capital letters.