traits:

php only supported single inheritance , a child class can inherit from one single Parent class ,if we need multiple behaviours from more then one class,traits solve this problem .

trait message1
{
    public function msg1()
    {
        echo "OOP is fun! ";
    }
}
trait message2
{
    public function msg2()
    {
        echo "OOP reduces code duplication!";
    }
}
class Welcome
{
    use message1; //trait-1 
}
class Welcome2
{
    use message1, message2; // trait-1 and trait-2
}

$obj = new Welcome(); //has access of all methods of only trait-1 
$obj2 = new Welcome2(); //has access of all methods of trait-1 and 2
$obj->msg1();
// $obj->msg2();
$obj2->msg1(); 
$obj2->msg2();

static method:

Static methods can be called directly without creating instance of the class.static methods are declared with the static keyword

class greeting{
    public static function welcome(){
        echo "hello php";
    }
}
greeting::welcome() ; 
echo "\n";

calling a static method from another class non-static method

class A
{
    public static function welcome()
    {
        echo "Hello World!";
    }
}
class B{
    public function msg(){
        A::welcome();
    }
}
$b = new B() ; 
$b->msg() ; 
echo "\n";

another example for static method

class domain{
    protected static function getWebSiteName(){
        return "mhdyhasan.com";
    }
}

class domainW3 extends domain{
    public $webName ; 
    public function __construct()
    {
        $this->webName = parent::getWebSiteName();
    }
}
$d = new domainW3() ; 
echo $d->webName ; 
echo "\n";

example of static properties in class

class pi
{
    public static $value = 3.14159;
    public function staticValue()
    {
        return self::$value;
    }
}

$pi = new pi();
echo $pi->staticValue();

echo "\n";

example for static properties in child class

class pi{
    public static $value = 3.1416 ; 
}
class x extends pi{
    public function Xstatic(){
        return parent::$value ; 
    }
}
echo x::$value ; 
echo "\n";
$v = new x() ; 
echo $v->Xstatic();
echo "\n";