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Everything that we've put [br]in our webpages so far

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has been either [br]content displayed by the browser,

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or tags to tell the browser [br]how to display it.

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Sometimes though, we just want to put [br]information in our webpages

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for other humans to read, [br]and for the browser to ignore.

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To do that, we write [br]an opening angle-bracket,

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an exclamation mark, [br]two dashes,

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and some text inside here,

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and then two dashes [br]and a closing angle-bracket.

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We call this a comment.

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And it's something that we do [br]in all sorts of programming languages,

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because we often want to do things [br]that are just for humans.

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That's the thing about programs: [br]

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they're not just [br]for computers to look at,

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they're also for [br]other humans to look at.

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Because we often work together [br]on things and learn from each other.

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Okay, what do we use comments for,

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besides just saying "hello" [br]to our fellow humans?

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Well, we might use them for [br]letting people know

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where content came from, [br]in case they want to update it.

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I'll say, "This paragraph is based on [br]the Wikipedia article,"

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and I should probably [br]give a link to that, too, but...

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And, "This paragraph is based on [br]Pamela's personal opinion,"

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a very well trusted source.

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Then maybe we'd even, say, [br]give a link inside the comments,

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and say, "These lyrics were from here."

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And that helps people know [br]how I got the content of this page.

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Do you notice something [br]about these comments?

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They are all green.

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That's because we're using a code editor [br]with syntax highlighting,

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and it uses colors to help us [br]see what's what,

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and comments are pretty much [br]always colored green, by convention.

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We could also use comments to [br]"comment out" parts of our HTML.

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Like if we want to experiment with[br]taking something away from our webpage.

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We just surround it with a comment.

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♪ (humming) ♪

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Now, the browser [br]no longer sees that HTML,

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because browsers ignore [br]everything in comments,

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and that part is gone from the page.

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If I decide that I actually liked it, [br]I can comment it back in

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by removing those comments [br]on both sides...

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and now it's back!

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Remember, comments are for humans.

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At least, the kind of humans that [br]like to look at webpage code.

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Which is pretty much [br]all of us now, right?