Since the other two answerer have given definitions, I'll try to give you a realistic example to make it a little more understandable (and hopefully it makes sense)
Object oriented programming does treat things as objects which can possess traits and properties (the fields) and perform or be affected by an action (the methods).
Say your using object oriented programming to handle the front end side of a program which stores customer data. It would most likely store the data on the back side in some sort of database.
Every time you have a customer, you need to create a new customer. The class is like a factory, so you most likely will have a customer class. The customer class will contain constructors, which define what properties each object has. You can just have 1 constructor, but usually there are a series of them, and which one is created depends on which parameters you pass in. So something like (in java.. sorry if my syntax is inconsistent, I've been programming a lot of different languages lately.)

Customer cust1 = new Customer();

That gives you a customer object, with the name cust1. It would also call the default constructor because the parenthesis are blank (not passing in any info to the constructor), so whatever the Constructor gives it is what it has. This could be nothing (just a blank customer) or it could have things like

string birthDate;
string address;
string phoneNumber
int numOfPurchases

Which are most likely initialized to NULL. It's just saying that the customer HAS a birth date (but the birth date hasn't been determined), the customer HAS an address (which isn't determined), and etc. your numOfPurchases will almost always be set to 0, since a new customer won't have made any purchases yet.
You may then have another constructor that takes in that information, so maybe your call is
:
Customer cust2 = new Customer("Feb 20th 1975", "123 Maple Street", "555-5555")

The number of purchases might be set from within the constructor since it's going to be the same for every customer.
Realistically, that information would be pulled out of a form or other user input rather than hard coded.
So cust2 now HAS a birth date, and it's been defined as Feb 20th 1975, they HAVE a phone number, which is 555-555, and etc.
So birth date, address, and phone number, and number of purchases are the properties which each employee has. You can change one of the properties without changing the whole employee, like

cust2.PhoneNumber = "519-2345";

which is going to set the phone number property of cust2 to 519-2345.

Because each of these properties is like a trait of an object, if the object is deleted, it's properties are too. So if you delete cust2 out of the system, it's phone number, birth date, and address disappear too unless you copy that information elsewhere first - but it's not really useful without the object. The number of purchases is the only one that may want to be kept, just for sales statistics.

Then there are methods which can affect each object. So in the case of a customer, you might have something like updating the fields (which is likely most common).

Each time a purchase is made, you want to increase the number of purchases by one. Think of methods as actions, and often, each one is named with a verb.
So you'd have something like:

public int buySomething()
{
numOfPurchases = numOfPurchases + 1;
return numOfPurchases;
}

Of course, it would likely have much more code, since it is called when you buy something, like you might want to calculate costs from here or get more information or whatever. In this case, you are passing nothing in and returning an int representing the new number of purchases

Then, you call that method with your customer, so:

int purchases = cust1.buySomething()

This would buySomething with cust1, and since it is returning an integer, your saving that integer to the variable purchases, which could then be used for something like displaying the number of purchases on the screen. You could also have no return, and then you'd just assume that it worked.

Does that give you the start of an idea about what OOP is, or do you want me to explain anything else?

Wikipedia does a fairly good job of explaining the concepts so you might want to check that out here

Good luck!
Source(s):
3rd year programming student that has taken -
Java
C++
C#
Visual Basic
SQL
HTML & CSS
and way too many more that I can't keep them all straight.


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