Whenever I go to YouTube or any website at all, it doesn’t matter if I write the website name in lowercase letters or uppercase letters, I will land on the same website. But whenever we go to a video and even replace 1 letter with lowercase or uppercase, the link doesn’t work.
How does the URL know that one section is not case-sensitive while the other section is case-sensitive?
I can understand why that’s the case. To keep the URLs unique. just in case something similar comes up. But what’s happening behind the scenes?
In: 52
With example: https://www.youtube.com/watch?v=Coz0JC1nnJI
Domain names (youtube.com) and their subdomains (www.youtube.com) are case-insensitive according to [RFC 4343](https://datatracker.ietf.org/doc/html/rfc4343). Everything after the domain (watch?v=Coz0JC1nnJI) is passed to the application server, without any changes, who can then treat that data in a case-sensitive fashion *if they want too* [like YouTube is doing].
In YouTube’s case, they are leveraging capital letters so that they can reference a greater number of videos, with such a short identifier. Here is an obligatory reference to Tom Scott’s (https://www.youtube.com/watch?v=gocwRvLhDf8).
With example: https://www.youtube.com/watch?v=Coz0JC1nnJI
Domain names (youtube.com) and their subdomains (www.youtube.com) are case-insensitive according to [RFC 4343](https://datatracker.ietf.org/doc/html/rfc4343). Everything after the domain (watch?v=Coz0JC1nnJI) is passed to the application server, without any changes, who can then treat that data in a case-sensitive fashion *if they want too* [like YouTube is doing].
In YouTube’s case, they are leveraging capital letters so that they can reference a greater number of videos, with such a short identifier. Here is an obligatory reference to Tom Scott’s (https://www.youtube.com/watch?v=gocwRvLhDf8).
Everything is case sensitive because the binary representation of upper and lower case letters is different.
It’s a deliberate choice to create a program or operating system that does not distinguish between lower and upper case.
Everything is case sensitive because the binary representation of upper and lower case letters is different.
It’s a deliberate choice to create a program or operating system that does not distinguish between lower and upper case.
I’m general computers don’t just think a capital letter and a lower case letter are the same thing. Basically at the end of the day each character is converted to some number. So you can think of lowercase a-z as being 1-26 and then capital A-Z and 27-52. Sometimes programmers recognize the capitalization doesn’t matter and will automatically convert all characters one way or another before working with that you typed in. This is likely what the Internet service providers and DNS systems are doing. Sometimes they do care like YouTube who wants more unique IDs so they treat capitals differently. The difference is what system is interpreting what part of the url. The domain name isn’t handled by YouTube and the routing after the domain is
I’m general computers don’t just think a capital letter and a lower case letter are the same thing. Basically at the end of the day each character is converted to some number. So you can think of lowercase a-z as being 1-26 and then capital A-Z and 27-52. Sometimes programmers recognize the capitalization doesn’t matter and will automatically convert all characters one way or another before working with that you typed in. This is likely what the Internet service providers and DNS systems are doing. Sometimes they do care like YouTube who wants more unique IDs so they treat capitals differently. The difference is what system is interpreting what part of the url. The domain name isn’t handled by YouTube and the routing after the domain is
When your nan sends you a card for your birthday the man at her post office will send it through to your town because he knows that this is a town. This is like the “YouTube.com” bit. When it gets to your town your postman gets it but if she’s written your street wrong he won’t be able to find your house. This is what YouTube do when it gets to them and you’ve put the unique part wrong. If the card has the right town and street then it’ll get to your house for your birthday. This is the same as if you’ve written it all right and YouTube know what video you’d like to watch.
When your nan sends you a card for your birthday the man at her post office will send it through to your town because he knows that this is a town. This is like the “YouTube.com” bit. When it gets to your town your postman gets it but if she’s written your street wrong he won’t be able to find your house. This is what YouTube do when it gets to them and you’ve put the unique part wrong. If the card has the right town and street then it’ll get to your house for your birthday. This is the same as if you’ve written it all right and YouTube know what video you’d like to watch.
Any application can be case sensitive, or case insensitive.
* case insensitive: A equals a
* case sensitive: A does not equal a
The domain name system that lets you get to a web site is case insensitive. You will land at that domain regardless of upper or lower case. Usually the path under that domain is case insensitive because the web server is told to ignore case. Reddit paths are case sensitive, go to the privacy policy page but with a capital P, and it won’t take you there.
So let’s take this YouTube URL:
[https://youtu.be/dQw4w9WgXcQ](https://youtu.be/dQw4w9WgXcQ?si=0ahfosjYz1attRmv)
(Yeah, I went there) You could type that:
[https://YOUTU.be/dQw4w9WgXcQ](https://YOUTU.be/dQw4w9WgXcQ)
And you’ll still get there because domains aren’t case sensitive.
But the jumbled letters aren’t a path, so there’s no web server case setting to make. Those letters are a publicly available ID for which video to serve up. It’s your input into the YouTube program that tells it to find that video. YouTube has decided that a video ID is a mix of upper and lower case.
Edit: Typoed wrong way
Any application can be case sensitive, or case insensitive.
* case insensitive: A equals a
* case sensitive: A does not equal a
The domain name system that lets you get to a web site is case insensitive. You will land at that domain regardless of upper or lower case. Usually the path under that domain is case insensitive because the web server is told to ignore case. Reddit paths are case sensitive, go to the privacy policy page but with a capital P, and it won’t take you there.
So let’s take this YouTube URL:
[https://youtu.be/dQw4w9WgXcQ](https://youtu.be/dQw4w9WgXcQ?si=0ahfosjYz1attRmv)
(Yeah, I went there) You could type that:
[https://YOUTU.be/dQw4w9WgXcQ](https://YOUTU.be/dQw4w9WgXcQ)
And you’ll still get there because domains aren’t case sensitive.
But the jumbled letters aren’t a path, so there’s no web server case setting to make. Those letters are a publicly available ID for which video to serve up. It’s your input into the YouTube program that tells it to find that video. YouTube has decided that a video ID is a mix of upper and lower case.
Edit: Typoed wrong way
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