What is the difference between char and varchar data types? | PHP

Set char to occupy n bytes and it will take n bytes even if u r storing a value of n-m bytes
Set varchar to occupy n bytes and it will take only the required space and will not use the n bytes
eg. name char(15) will waste 10 bytes if we store 'romharshan', if each char takes a byte
eg. name varchar(15) will just use 5 bytes if we store 'romharshan', if each char takes a byte. rest 10 bytes will be free.