Welcome! Today's subject is Encapsulation, a cornerstone of Object-Oriented Programming (OOP). Encapsulation bundles data and the operations that we perform on them into one unit, namely an object. It guards data against unwanted alterations, ensuring the creation of robust and maintainable software.

Prepare yourself for an exciting journey as we delve into how encapsulation works and explore the vital role it plays in data privacy.

Starting with the basics, encapsulation is similar to packing data and the methods that modify this data into a single compartment known as a class. It safeguards the data in an object from external interference.

To illustrate, consider a PHP class representing a bank account. Without encapsulation, the account balance could be directly altered. With encapsulation, however, the balance can only change through specified methods, like depositing or withdrawing.

Encapsulation restricts direct access to an object's data and prevents unwanted data alteration. This principle is comparable to window blinds, allowing you to look out while preventing others from peeping in.

In encapsulation, private and public attributes are integral to data privacy. Private attributes, indicated by the private keyword, require caution when being manipulated.

To illustrate, let's consider a PHP class named Person, which includes a private attribute name.

In this example, name is private, and getName() enables us to access name. However, we don't provide a method to change the name, preventing alterations.

To designate an attribute as private, we use the private keyword.

Within encapsulation, PHP uses getter and setter methods to access or modify private attributes. In a class, the getter method retrieves the attribute value, and the setter method alters it. Let's illustrate this.

Here, setName() and getName() serve as the setter and getter methods, respectively, for the private attribute name.

Let's apply the principle of encapsulation to our BankAccount class, which includes private attributes like an account number and balance, along with public methods for withdrawals, deposits, and balance checks.

In the above code, the BankAccount class encapsulates account details that we would like to be hidden from the outer scope, and the public methods manipulate the balance in a controlled way. This way, we limit the potential interaction with the account's balance and other private information, improving security.

Admirable! Now it's your turn to apply what you've learned by practicing encapsulation in PHP. Next, we will have some practice exercises. Are you ready?

Remember, practice enhances your comprehension. Enjoy coding!