Why do we use script language="php" ? How it effects the code?plus is echo like "cin"

Answer 1

echo like cout

Answer 2

php is a server-side ( back-end ) scripting language, it's used along with database to manipulate data on the hosting, not the webpage like if you wanna send emails or create a registration system for clients to sign up and create password, you use php (but surely you can manipulate webpages too). echo is the equivalent of cout, not cin, as it outputs on the page and doesn't prompt used for input.