Sentence case online tool makes the first letter in each sentence uppercase (capital letter). This is a standard way to write articles in most of the worldwide languages including English. Only the first letter is capitalised (if that character is alphabetic) and another characters and words remain lowercase.
Please note that in each language might be some exceptions where nouns are capitalised by specific rules. For example in English the titles, names of persons, streets, buildings or mountains, etc (e.g. Mr. John, The White House, Fuji, World War).
This online tool works super easy. Just write or paste in your text in input text to be converted into Sentence case and click on convert to Sentence case button. Here you go! In a second your desired content has been converted into Sentence case. As you can see every first letter of each sentence has been capitalised.
If you need to convert the whole content into lowercase or UPPERCASE, use one of tools from the related tools below. Also you can find there Start case online converter tool, which converts the first letter of every word.