Explain the basic syntax and structure of PHP code.

The basic syntax and structure of PHP code follow a set of rules that define how PHP scripts are written. Understanding this syntax is fundamental for writing PHP code effectively. Let's dive into the details:

1. Opening and Closing Tags:

* PHP code is enclosed within `<?php` and `?>` tags.
* These tags indicate the start and end of PHP code within an HTML document.
2. Outputting Content:

* To output content or variables to the browser, you use the `echo` statement or `print` function.
* For example, `echo "Hello, World!";` or `print("Welcome!");`.
3. Variables:

* Variables in PHP start with a dollar sign (`$`) followed by the variable name.
* Variable names are case-sensitive and can contain letters, numbers, and underscores.
* Variables do not require explicit type declaration.
* Example: `$name = "John Doe";`.
4. Comments:

* PHP supports single-line and multi-line comments for code documentation and readability.
* Single-line comments start with `//` or `#`.
* Multi-line comments are enclosed between `/*` and `*/`.
* Example:
```
arduino`// This is a single-line comment

/
This is a
multi-line comment
/`
```
5. Data Types:

* PHP supports various data types, including strings, integers, floats, booleans, arrays, objects, and more.
* Variables dynamically assume the appropriate data type based on assigned values.
* Example: `$message = "Hello"; $age = 25; $price = 9.99; $isReady = true;`.
6. Operators:

* PHP supports a wide range of operators, including arithmetic, assignment, comparison, logical, and string concatenation operators.
* Arithmetic operators: `+`, `-`, `*`, `/`, `%` (modulo).
* Assignment operators: `=`, `+=`, `-=` and others.
* Comparison operators: `==`, `!=`, `>`, `<`, `>=`, `<=`.
* Logical operators: `&&` (AND), `||` (OR), `!` (NOT).
* String concatenation: `.` (dot).
* Example: `$result = 10 + 5; $isTrue = ($result > 15) && ($result < 20);`.
7. Conditional Statements:

* PHP provides conditional statements to execute different blocks of code based on specified conditions.
* Common conditional statements are `if`, `else`, `elseif`, `switch`, and ternary operator (`? :`).
* Example:
```
php`if ($age < 18) {
echo "You are a minor.";
} elseif ($age >= 18 && $age < 65) {
echo "You are an adult.";
} else {
echo "You are a senior citizen.";
}`
```
8. Loops:

* PHP offers loop structures for repetitive execution of code blocks.
* Common loop structures are `for`, `while`, `do-while`, and `foreach`.
* Example:
```
php`for ($i = 1; $i <= 10; $i++) {
echo $i . " ";
}

$numbers = [1, 2, 3, 4, 5];
foreach ($numbers as $number) {
echo $number . " ";
}`
```
9. Functions:

* PHP allows you to define and use functions for code reusability and modularity.
* Functions encapsulate a block of code and can accept