Foundations

Links and Images

Foundations Course

Introduction

Links are one of the key features of HTML. They allow us to link to other HTML pages on the web. In fact, this is why it’s called the web.

In this lesson, we will learn how to create links and add some visual flair to our websites by embedding images.

Lesson overview

This section contains a general overview of topics that you will learn in this lesson.

  • How to create links to pages on other websites on the internet.
  • How to create links to other pages on your own websites.
  • The difference between absolute and relative links.
  • How to display an image on a webpage using HTML.

Preparation

To get some practice using links and images throughout this lesson we need an HTML project to work with.

  1. Create a new directory named odin-links-and-images.
  2. Within that directory, create a new file named index.html.
  3. Open the file in VS Code and fill in the usual HTML boilerplate.
  4. Finally, add the following h1 to the body:
<h1>Homepage</h1>

Anchor elements

To create a link in HTML, we use the anchor element. An anchor element is defined by wrapping the text or another HTML element we want to be a link with an <a> tag.

Add the following to the body of the index.html page we created and open it in the browser:

<a>click me</a>

You may have noticed that clicking this link doesn’t do anything. This is because an anchor tag on its own won’t know where we want to link to. We have to tell it a destination to go to. We do this by using an HTML attribute.

An HTML attribute gives additional information to an HTML element and always goes in the element’s opening tag. An attribute is usually made up of two parts: a name, and a value; however, not all attributes require a value. In our case, we need to add an href (hypertext reference) attribute to the opening anchor tag. The value of the href attribute is the destination we want our link to go to.

Add the following href attribute to the anchor element we created previously and try clicking it again, don’t forget to refresh the browser so the new changes can be applied.

<a href="https://www.theodinproject.com/about">click me</a>

By default, any text wrapped with an anchor tag without an href attribute will look like plain text. If the href attribute is present, the browser will give the text a blue color and underline it to signify it is a link.

It’s worth noting you can use anchor tags to link to any kind of resource on the internet, not just other HTML documents. You can link to videos, pdf files, images, and so on, but for the most part, you will be linking to other HTML documents.

Images

Websites would be fairly boring if they could only display text. Luckily HTML provides a wide variety of elements for displaying all sorts of different media. The most widely used of these is the image element.

To display an image in HTML we use the <img> element. Unlike the other elements we have encountered, the <img> element is self-closing. Empty, self-closing HTML elements do not need a closing tag.

Instead of wrapping content with an opening and closing tag, it embeds an image into the page using a src attribute which tells the browser where the image file is located. The src attribute works much like the href attribute for anchor tags. It can embed an image using both absolute and relative paths.

For example, using an absolute path we can display an image located on The Odin Project site:

See the Pen absolute-path-image by TheOdinProject (@TheOdinProjectExamples) on CodePen.

To use images that we have on our own websites, we can use a relative path.

Linux, macOS, ChromeOS
  1. Create a new directory named images within the odin-links-and-images project.
  2. Next, download this image and move it into the images directory we just created.
  3. Rename the image to dog.jpg.
WSL2

When you download a file from the internet, Windows has a security feature that creates a hidden Zone.Identifier file with the same name as your downloaded file and it looks like mypicture.jpg:Zone.Identifier This file is harmless, but we’d like to avoid copying it over and cluttering up our directories.

  1. Create a new directory named images within the odin-links-and-images project.

  2. Next, download the stock dog image.

  3. Right click on the new download at the bottom of the chrome window and select “Show in folder”.

    1. Alternatively, if you do not see anything at the bottom of the chrome window, open the “Customize and control Google Chrome kebab menu and select the “Downloads” item. This will show all of your downloads, each with its own “Show in folder” button.
  4. Drag the file from your downloads folder to VSCode’s file browser into your new images directory.

    1. Alternatively, using your Ubuntu terminal, navigate to the folder you want to copy the image to (cd ~/odin-links-and-images for example)

    2. Type cp <space>

    3. Drag the dog.jpg image from a Windows Explorer window and drop it onto the terminal window, it should appear as "/mnt/c/users/username/Downloads/dog.jpg"

    4. Type <space> . to tell cp that you want to copy the file to your current working directory.

      1. The full command will look something like cp "/mnt/c/users/username/Downloads/dog.jpg" .
    5. Hit Enter to complete the command, and use ls to confirm the file now exists.

Dragging files from Windows into the VSCode file browser prevents the Zone.Identifier files from being copied over. From now on, any time you need to copy pictures or other downloaded files like this into WSL2, you can do it in this way. If you ever accidentally copy these Zone.Identifier files into WSL2, you can safely delete them without any issue.

Finally add the image to the index.html file:

<body>
  <h1>Homepage</h1>
  <a href="https://www.theodinproject.com/about">click me</a>

  <a href="./pages/about.html">About</a>

  <img src="./images/dog.jpg">
</body>

Save the index.html file and open it in a browser to view Charles in all his glory.

Parent directories

What if we want to use the dog image in the about page? We would first have to go up one level out of the pages directory into its parent directory so we could then access the images directory.

To go to the parent directory we need to use two dots in the relative filepath like this: ../. Let’s see this in action, within the body of the about.html file, add the following image below the heading we added earlier:

<img src="../images/dog.jpg">

To break this down:

  1. First, we are going to the parent directory of the pages directory which is odin-links-and-images.
  2. Then, from the parent directory, we can go into the images directory.
  3. Finally, we can access the dog.jpg file.

Using the metaphor we used earlier, using ../ in a filepath is kind of like stepping out from the room you are currently in to the main hallway so you can go to another room.

Alt attribute

Besides the src attribute, every image element must also have an alt (alternative text) attribute.

The alt attribute is used to describe an image. It will be used in place of the image if it cannot be loaded. It is also used with screen readers to describe what the image is to visually impaired users.

This is how the The Odin Project logo example we used earlier looks with an alt attribute included:

See the Pen image-alt-attribute by TheOdinProject (@TheOdinProjectExamples) on CodePen.

As a bit of practice, add an alt attribute to the dog image we added to the odin-links-and-images project.

Image size attributes

While not strictly required, specifying height and width attributes in image tags helps the browser layout the page without causing the page to jump and flash.

It is a good habit to always specify these attributes on every image, even when the image is the correct size or you are using CSS to modify it.

Here is our Odin Project logo example with height and width tags included:

See the Pen Image Height and Width Attributes by Brian Lister (@FabulousPBB) on CodePen.

Go ahead and update the odin-links-and-images project with width and height tags on the dog image.

Assignment

Knowledge check

This section contains questions for you to check your understanding of this lesson on your own. If you’re having trouble answering a question, click it and review the material it links to.

Additional resources

This section contains helpful links to related content. It isn’t required, so consider it supplemental.

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