In the Bible text translators use a parentheses and Brackets. Like in
1. John 7: 50 KJV reads: ? Nicodemus saith unto them, (he that came to Jesus by night, being one of them,)?
2. John 8:24 KJV reads: ?I said therefore unto you, that ye shall die in your sins: for if ye believe not that I am he, ye shall die in your sins.?
3. Matthew 18:11 HCSB reads: [For the Son of Man has come to save the lost.]
My question is why they wrap texrt in ( ), [ ] and italic text?
What do these symbols mean to original bible canon text?