 While most developers know what a URL is, not everyone knows what a URI is, and even less knows about URINs. Not to mention that the relationship among these items is not always very clear. After watching this video, you will understand the differences among URLs, URINs, and URIs. If you navigate on the internet, you deal with URLs every day. URL stands for Uniform Resource Locator. Maybe the expended name may sound a little bit weird to you, but you can think of it as an address, like your home address. Yes, it contains all of the information to find your home. Similarly, you can define a URL as a string that denotes the location of a given resource on the internet. It could be a web page, an image, a mailbox, and any other resource. These are examples of URLs. While the terms URL and link are commonly used interchangeably, like they mean the same thing, technically, they are not synonyms. A URL is a string that allows you to locate a resource. A link, short for hyperlink, on the other hand, is an HTML element that enables you to load the resource from a given URL in a browser. So a link relies on a URL and the URL can exist without a link. But without a URL, links makes no sense, at least not in its original meaning. If you think about what a URL is, the uniform part of the acronym tells us that every URL should follow a common structure of these locator strings. If you take a look at this image, it shows the extended structure for a given URL. In this case, a URL that represents the address of one of the samples we have at Auth0's Developer Hub. A URL consists of a few parts. The scheme in a URL, this is the protocol that should be used to access the resource. Beyond the well-known HTTP and HTTPS, you may use any other teams, if you like, like FTP, SMTP, and so on. The domain is the part that indicates the server hosting the resource. It can be a domain name or an IP address. The port is the protocol port which to send the request to to access that resource. Usually it is omitted, meaning that the full protocol port should be used. We have the path that is the path of the resource on the hosting server, and we have parameters. These are optional astra information provided to the hosting server. And finally, we have the anchor that represents a specific part inside of the resource. It is also called a fragment. It is worth mentioning that the group consisting of the domain name and the port, if it is present, is also known as the authority. The scheme and the authority are separated by a column for slash, for slash string. If, by any chance, the URL has no authority, the scheme and the rest of the URL are separated only by a column. A typical example of a URL without the authority port is that URL that represents an email address, such as mail to column your friend at somewhere.com. Speaking of Auth0, if you are going to configure your application to use Auth0, make sure you do not confuse two common concepts that are often mentioned by the documentation and the quick starts. And also the tutorials. The tenant domain or simply domain is a string in the form of your tenant.auth0.com. The your tenant name part is the name that you provided when you created your Auth0 account. It represents the service domain name that will handle all of the interactions between your application and Auth0. The issuer URL is the base URL of your tenant preceded by the scheme. It is the issuer of ID and access tokens and is going to be used to handle authentication and authorization in your applications. As you can see, while the issuer URL follows the URL format, the tenant domain is just the domain part of a URL. The URI acronym stands for Uniform Resource Identifier. Shortly, it is a string that identifies a resource. From a hypothetical point of view, a URI string mostly follows the same format as... Yes, you guessed it, a URL. And now you may be wondering, how is that possible? Are URLs and URIs the same thing? Well, not really. Both URLs and URIs follow the same specification. They are RFC 3986. However, while URIs allow you to locate a resource, a URI simply identifies a resource. This means that a URI is not necessarily intended as an address to get a resource. It is meant just as an identifier. Going back to the address example, if you say you live in the only yellow house in your town, you are not giving directions on how to get there. However, this information identifies your house among others in your town. On the other hand, a URL is a URI. Beyond the fact that it uses the same URI syntax, it also identifies a resource through an address. In other words, a URL is an identifier that allows you to identify your resource and, at the same time, gives you directions to access it. Your home address not only gives directions to find it, it also identifies it so that you can't confuse it with another one. In a nutshell, URLs are a subset of URIs. At this point, you are probably wondering, what is the point of a URI that is not an address of a resource? Well, a typical example of a URI that is not a URL is an XML namespace identifier. If you've ever worked with XML, you may have found some documents similar to this one. That the great chat.com languages recipe string is a URI that identifies the XML namespace. It is a set of names for the XML elements and attributes that allows you to define a cooking recipe. Oh, by the way, don't use the namespace. I totally invented it just for this video. Although the format of the URI is the same as the URL, it doesn't allow you to access any resource on the web. However, using the format lets you reduce name clashing for namespaces. In fact, the domain name of a given URI is not intended as the name of a server hosting that resource. The URI domain name leverages the existing registration process for a DNS to obtain a globally unique name without the need for another registry. In other words, if you are the owner of the great chat.com domain, there is no risk in creating URIs based on this domain. URIs have great relevance in the semantic web, since they are used to identify concepts through the resource description framework or RDF for short. As another example of a URI that is not a URL, consider the registration of an API without zero. When registering your API without zero, you need to provide an API identifier that is also known as an audience. This identifier is nothing but a URI, a logical identifier for your API. This image shows the example of an audience in the URI format. Our zero will not attempt to make any requests to that URI. It's just used to distinguish your API from others. Now, speaking of URIs, maybe the URI acronym is less popular than URL and URI. But it belongs to the same family and stands for Uniform Resource Name. And its scope is to identify resources in a permanent way, even after that resource no longer exists. Unlike a URL, a URI doesn't provide any information about locating the resource, but it simply identifies it just as a pure URI. In particular, a URI is a URI whose scheme is the URI type and has the following structure, as described by the IFC 2141. The namespace identifier placeholder stands for a string representing the resource category you want to identify. The namespace specific string is the resources specific identifier. And its format depends on the namespace identifier. These are examples of your ends. And they identify objects of different types. For example, the first one identifies the publication to the ISBN system. The second one identifies the publication through the ISSN system. And the last one is an RFC issued by IETF. You may think that this format differs a lot from the URL and the URI format that you've seen earlier. But actually, they have a common syntax definition. Although the difference has starkest reasons for existing. In the R0 context, you use URI ends to globally identify your SAML entity. Specifically, you use the URI in the form of URI column, R0 column, your tenant column, your connection name. Unlike the URI, URI ends are identifiers issued by a public standard organization and may involve anything needing a standard identifier in a human activity, not just computers and software. Now you have a clear picture of the relationship between URLs, URIs and URI ends. If you need a refresher at any time, you can come back to this video or to this great infographic that I have linked below for you to download. In the description of this video, you will also find the blog post written by my colleague Andrea Chiarelli and with all of the information that you saw today. I'm looking forward to your comments and questions in the comment sessions below and I hope I'll talk to you soon. Bye.