Where does code come from? Computer programming is composing and organizing a collection of instructions in a language the computer understands. Programs can be as different as scientific calculators, databases and animation software. A computer can't think for itself, so people have to give it instructions. Computer science is the study of computers and computing, including algorithms, hardware, software and how they are used to process information. Let's take it a piece at a time.

First, Ada Lovelace. She was an English mathematician who worked with Charles Babbage. She created a program for his planned computer. She has been called the first computer programmer. She was born on December 10, 1815, and died on November 27, 1852. An algorithm is a list of steps for solving a problem or getting something done. The word algorithm comes from the Latin form of the name of the scholar al-Khwarizmi. Let's keep her name and that word in mind as we go on.

Next, Grace Hopper. She was born on December 9, 1906. She was an American mathematician and a rear admiral in the U.S. Navy. She helped develop computer technology, including UNIVAC I, the first commercial electronic computer. She also made an early tool that let people give a computer instructions in English-like words instead of numbers. A compiler translates code written in a language people can read into the machine code a computer can run. Let's see what her work did, one step at a time.

Why would anyone want English-like words? Look at what a computer runs. Computers run on binary code, where each digit is either off or on, written 0 or 1. Machine language is made of the numeric codes a computer can run directly. Machine and assembly languages are low-level, while high-level languages are easier for people to read and write. An IBM team led by John Backus made FORTRAN, a programming language that uses English-like statements. Let's go through the words slowly, so that each one makes sense. Here is a look at how they fit together.

Python is one high-level language. Python is a general-purpose programming language. It was developed by Guido van Rossum in 1991. It was named after the British television series Monty Python's Flying Circus, and it was publicly released in 1994. Python is open source, so anyone can use it for free. Python has had three main versions: Python 1.0 in 1994, Python 2.0 in 2000 and Python 3.0 in 2008. Python 3.0 is not backward-compatible with earlier versions. Let's look at it step by step, from the year it began to the year of each new version. Here are the dates in order.

Python has a date to remember. The Python team decided that January 1, 2020, was the day they sunset Python 2, so Python 2 is no longer supported. Here is how Python runs. Python is an interpreted language, so its source code can be run directly, with no separate compiling step. Python source code is compiled into bytecode, the internal representation of a Python program that the interpreter runs. Python can be easy to pick up, whether you are a first-time programmer or you have used other languages. Here is a short look at how it works, so that you can see each part. Let's go over it once.

Here is a tool for kids. As of November 2026, Scratch is a coding tool where kids make their own stories, games and animations. Scratch was developed at the MIT Media Lab and released to the public in 2007. In 2019 Scratch was transferred from MIT to the Scratch Foundation, an independent nonprofit. Here is how the Scratch Foundation describes it as of November 2026: Scratch is built on blocks that kids drag and snap together, so there is no tricky syntax to type. Let's go over what that means in plain words, one fact at a time. Here is the story of one tool.

Now look inside a program. A variable is like a box that holds a value, and the value inside can change. Variables are not the values themselves. They are containers for values, and they can hold nearly anything, even whole functions. A Boolean is a value that can only be true or false. It is named after the English mathematician George Boole, who pioneered mathematical logic. A function can take inputs. The variables listed in a function definition are called parameters, and the values passed in when it is called are called arguments. Here is a short way to see it. Let's go through each idea, one at a time, and think about what it means.

Even good programmers make mistakes. A mistake in a computer program is called a bug. There are syntax bugs, which are typing mistakes in the code, and logic bugs. Programmers test a program to look for bugs. Programmers can find a bug by checking a program one small step at a time. Debugging means finding and fixing the bugs in a program. It is okay to make mistakes in a program, because finding and fixing bugs is a good way to learn. Let's look at what that means in plain words.

Here is a last idea. Computational thinking could be described as 'thinking like a computer scientist', and it is an important skill for everyone to learn, whether or not they want to be a computer scientist. As of November 2026, Code.org launched in 2013 with a video arguing that every student should learn computer science. Its Hour of Code later gave millions of students a chance to write their first line of code.

Words to know

• algorithm: list of steps
• compiler: code translator
• Boolean: true or false
• bytecode: internal form
• parameters: function inputs