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Whenever you run your application, there are so many moving parts.

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The key parts are the CPU, the cores and the thread.

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In this lesson, you will learn to tell the difference between CPU, core and thread.

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Now, a CPU is often referred to as a processor, and most computers only have one CPU chip.

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And so why is a CPU called the processor?

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That's because it uses processing units called course to execute instructions.

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The following is a four core CPU.

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Think of every corner as a worker.

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Whenever we write code, we're writing instructions.

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And when we were in our application, we're running our code on a thread.

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This thread contains the instructions that we programmed and all of the instructions that we programmed

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on this thread.

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They're sent over to the processor.

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We're sending these instructions to the processor and it's the cause the workers inside the processor

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that execute tasks based on the instructions that the thread provides.

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And it follows that the more cores you have, the more instructions that can be processed at the same

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time.

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Here's an exercise for you.

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Go on Google and look up how to check the number of CPU cores inside your machine.

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We'll give you some time to parse the video.

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OK.

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As of this recording, I'm using a MacBook Air M1, which has an eight core CPU.

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OK, now what is a thread, a thread is a path of execution.

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The instructions in your app run on a thread.

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Going back to our diagram, each thread acts as a pathway for instructions to flow through.

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Now, this is really important.

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So far, every application that we built in this course has been single threaded.

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I want to repeat this one more time.

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Every application that we built in this course has been single threaded.

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So every time we ran our single threaded application, the instructions were being run on a single thread.

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Our thread is like a conveyor belt of instructions and eventually every instruction is processed by

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the core and our core.

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Our worker processes tasks based on the instructions that it receives.

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Now, a multi-threaded application runs on many threads.

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When you run a multi-threaded application, different parts of the code are running on different threads.

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This can be more efficient because different parts of your code are being processed at the same time.

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And so once again, each threat is like a conveyor belt of instructions, and eventually every instruction

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gets processed by a court which performs tasks based on the instructions that it receives.

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And once every instruction has been processed, you in essence, run your application.

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Let's talk about the main thread.

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By default, your application is single threaded.

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The thread your code runs on is known as the main thread.

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If I run the following code, it's going to run it on the main thread.

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In other words, the series of instructions we programmed execute on the main thread, and the main

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thread is like a conveyor belt that passes every instructions to a single core and the core inside of

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your computer.

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It performs tasks based on the instructions that it receives from your main thread, thereby running

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your application.

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OK, let's recap what we learned so far.

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A CPU chip has multiple cores in each core is a worker that can perform tasks based on the instructions

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that it receives.

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Each thread is a conveyor belt of instructions that a core eventually processes.