The Fibonacci series is a sequence of numbers where each is the sum of the two preceding ones, starting from 0 to 1.

There are different ways to implement Fibonacci series generation in PHP. Below are two common approaches: using iterative loops and using recursion.

**Iterative Approach**: This method is straightforward and uses a loop to generate the Fibonacci sequence up to the desired length.**Recursive Approach**: In the recursive approach, the Fibonacci function calls itself to compute the value.

Remember, the recursive approach, although elegant, is less efficient for larger values of n due to the redundant calculations it involves. The iterative method is generally more efficient for larger sequences. If you want to generate a Fibonacci sequence for very large values of $n$, consider using memoization or other optimization techniques.