Despite PHP shifting more and more toward preferring Object-Oriented Programming, at its heart, PHP is a procedural language. All of the code is executed one line at a time, in the order that the parser receives it. To my mind, one of PHP’s strengths is blending a versatile object model along with procedural programming. Web applications can surface race conditions and dead locks more frequently, like any other program with potentially multiple concurrent users, as people update or work with the same resources.