PHP mt_srand() - Math Functions
What is mt_srand Function?
The mt_srand() function seeds the random number generator for mt_rand().This function should be called only once, and should be called before mt_rand() function.
In the above syntax "seed" specifies a seed number to the function to generate a random number.
In the above example the seed is given as a function mktime(), the random values are returned based on that.