# Working with Objects in C#: an overview

Object-oriented programming models software on the things around us, objects that each know some facts and do some jobs.

Novice · C# · OOP · Updated November 3, 2026

## After this lesson you can

- Explain how object-oriented programming models a program as objects

## Key takeaways

- Object-oriented programming models a program as objects, each knowing some facts about itself and doing some jobs.
- An object keeps data that belongs together in one place, such as a team's name, wins and losses, and only the object changes it.
- You've used objects already: a `string` knows its `Length` and can do jobs like `ToUpper()`.

So far, your programs have been lists of instructions, organized into methods. That works well for small jobs. But as programs grow, a long list of methods and loose variables gets hard to follow: which variables belong together? Which methods are allowed to change them?

**Object-oriented programming** (OOP) organizes a program differently. Instead of focusing only on methods and logic, you model your software on the world it serves, as **objects** with responsibilities.

## The world is made of objects

In daily life, objects are the **things** you work with. Think of a kitchen: it's full of objects, and each one has a purpose. The refrigerator keeps food cold. The dishwasher cleans dishes. The oven heats things up. You don't need to know how a refrigerator keeps things cold to use one; you open the door, put food in, and trust it to do its job.

Software objects work the same way. A shopping site might have a `Cart`, a `Product` and an `Order`. A sports app might have a `Team`, a `Game` and a `Player`. Each object:

- **knows** some facts about itself: a team knows its name, its wins and its losses;
- **does** some jobs: a team can record a game's result, or work out its winning percentage.

## Why build programs this way?

- **Things that belong together stay together.** A team's name, wins and losses travel as one object, not three loose variables.
- **Each object guards its own data.** Only the team changes its record, so a mistake can't creep in from anywhere in the program.
- **Programs read like the problem.** `team.RecordWin()` says what's happening, in the words of the problem.
- **Objects are reusable.** A `Team` written for one app works in the next.

You've used objects already. A `string` is an object: it knows its characters and its `Length`, and it can do jobs like `ToUpper()` and `Split()`. In this chapter you'll design and write objects of your own.

## Check yourself

1 question to try on the lesson page.

## So what

Object-oriented programming is how almost every large C# program is organized, from web apps to games: model the problem as objects, each knowing its own facts and doing its own jobs.

## Key terms

- [Object-Oriented Programming](https://www.ask-codey.com/glossary/object-oriented-programming)
- [Object](https://www.ask-codey.com/glossary/object-oop)

## Cheat sheets

- [Working with Objects in C#: an overview](https://www.ask-codey.com/cheat-sheets/working-with-objects-in-csharp-an-overview-cheat-sheet)

Source: https://www.ask-codey.com/lessons/working-with-objects-in-csharp-an-overview