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Let's now discover what are loops and how to use

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them with Python. So let's first understand why

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you need loops. I have created a very simple

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program here that prints Hello 10 times. Okay,

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let's run that program. And actually, yes, it

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prints Hello 10 times. But that's quite not

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convenient. And now what if I asked you to print

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Hello 100 times, or 1000 times? Well, you're not

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going to write 1000 lines of print Hello, no. So

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whenever you need to repeat some instructions,

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let's say more than two or three times, this is

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where you are going to use loops. And we're going

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to start with the for loop. So I'm going to remove

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all that, and instead, I'm going to do for i in

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range 10. So let's just follow along, and then I'm

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going to explain to you, print hello. If I execute

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this, I still have Hello printed 10 times, okay.

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So what happened here. You can use the for loop,

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so you start with for, and then you're going to

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use an index, okay, so the index, which is going

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to go through a range or through a list, and the

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convention for that index is to name it, i okay.

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So for i, and then in, what you can do is use

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range. So basically, if you use range, a range is

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a list, which goes from zero to this value minus

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one. So basically, this is going to go between

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zero and nine. Okay, so you have 10 elements

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between zero and nine. And then you have a colon

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here. So what is going to happen is that this is

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going to execute the next block of code which is

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indented here, as you can see, is going to execute

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for each index, okay, that you have for the range,

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okay? So it's going to execute it for i is equal

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to 0,1,2,3,4,5,6,7,8, and 9. So basically, with that,

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you just execute that block of code 10 times, and

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the indentation here is super, super important.

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I'm going to print test here, okay. So Hello, and

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then test 10 times, I click, play to run. And you

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can see Hello, test, Hello, test, 10 times. Now I'm

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going to remove the indentation here and see what

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happens. We have Hello 10 times and then test is

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just one time, okay, because with for loop

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you're going to execute this for 10 times. Only the

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instructions that are indented in that block of

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code. And then you continue the execution back to

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the normal indentation and you continue the

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execution of your program. Okay, so the

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indentation is super important. And one thing I'm

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going to show you is we can so we can actually

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print that i, so that i will be here an integer.

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So I can do Hello, and then plus, let's see str

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i. Okay, I cast the number to a string. And

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let's run that. And you can see now I have Hello,

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0, Hello 1, etc. Until Hello 9. So you can

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actually see what's happening here. So the i is

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going to take all the values between zero and 10

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minus one and then we can use that inside the

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loop. Now if I want to print 100 time, I just put

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100 here, and I run, and you can see we print Hello

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with 100 time with a different number every

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time. Okay, so that's very powerful. Here we've

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just two lines of code, we can print this 100 times.