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Remi : All programmers know the famous hello world program. But what is it? It's a computer program that simply displays hello world to the screen. Petra : In all programming languages, this is typically the first example that you will run. It helps you understand the very basics of the particular programming language you are learning. Remi : Guess who invented hello world. It was Brian Kernighan, a Canadian computer scientists who worked at Bell Laboratories with the two creators of the C programming language, Ken Thompson and Dennis Ritchie. Petra : Brian Kernighan and Dennis Ritchie co-wrote the first book on the C programming language in 1978. Here's how the book begins. "The only way to learn a new programming language is to write programs with it! The first program to write is the same for all languages, display the two words "hello world." Remi : What follows in the book is interesting because he confesses that to run this program is much harder than expected. One must create the program text somewhere, the source code, compile it correctly, load it into memory, run it, and then find where the result is displayed. Petra : This is still true today, but for you, the learners in this MOOC on C programming, we have simplified the steps a bit. You will have an online editor to enter the program, buttons for each of the necessary steps, compile, load, and run the code, and finally visualization modules will display the output of the program and other interesting features like what's happening with variables. You will learn about variables, too. Remi : Now it is your turn to use these tools and create your first computer program in the C programming language.