Redirects in Prestashop 1.7

Walkthrough

Redirects to Frontend

Tools::redirect("index.php");
Tools::redirectLink("index.php");
$this->canonicalRedirection("??");

Redirects to Backend

Tools::redirectAdmin("urlHere");
Tools::redirectAdmin($this->context->link->getAdminLink("AdminControllerHere"));
Tools::redirectAdmin(Context::getContext()->link->getAdminLink(AdminDashboard::class));

Going further

See how to generate an URL in Prestashop