What do you mean by Composer?
In PHP, a Composer is a tool which is used to manage application dependency. It allows us to declare the libraries of our project depends on and it will maintain all install & update them for you. It is not a package manager but it deals with "packages" or libraries, it manages them on a project basis, installing them in a directory inside our project.
The composer does not install anything globally by default. Laravel uses Composer to manage its dependencies. So, before using Laravel, make sure that you have to installed Composer on your system or server.
Click here to download If you don't have a composer.