Compare these two sentences:

• Click here to learn more about the Wadden Sea.
• Learn more about the Wadden Sea.

The first link text is meaningless, you have to read the whole sentence to understand what the click here is about. The second link text does that right away.

Visitors scan web pages for what they are looking for. Links stand out in the text, so make the text about where they lead. A link text should rather serve as a teaser, as clickbait for the scanning visitor.

So keep in mind that the golden rule is "Make link text meaningful and understandable on their own"

Compare these two ways of linking:

• Please don’t hesitate to e-mail or to call us.
• Please don’t hesitate to send a message to hello@a11y-collective.com or to call us at +31 (0)10 842 92 59.

In the first sentence, the actual e-mail address and telephone number are hidden. This will be a problem if someone wants to send an e-mail or make a call from another device than they one they’re now using. Showing the e-mail address or the number means the user can note it down for later reference, for instance.

How do you link to a file to be downloaded such as a PDF, a restaurant menu or a fact sheet, let’s say

Compare these two ways of linking a document:

• WebAIM Quick Reference: Web Accessibility Principles.
• WebAIM Quick Reference: Web Accessibility Principles (PDF, 327 Kb).

The first link looks like a normal link, but clicking it actually starts downloading a file. The second one lets the user know that clicking the file will start downloading a file, and tells them how big it is. If they’re on a train, for instance, they may wait until later before downloading. A link is a promise, not a surprise.

In some cases we want to add an image as a link and to be satisfied with the accessibility's aspect we will add some alt text that will describe our image.

but there is a tiny issue that will face our users that suffering from impaired vision when using a screen reader to read this text out loud, the alt text doesn't tell that image is a link,.

Take an image of a cherry tree, for instance:

• The image on the left is the wrong usage in our situation because it doesn't tell the truth
• The image on the right tell our user "Hey, i'm a link"

Underlining is the universal pattern for a link. Users get it right away. So use this pattern for links in paragraphs of text.

Links that are obviously links, such in navigation menus, don’t have to be underlined.

Oh, don't forget to read the image 😘

• Make links large enough, and include enough space between them and other links, so they are easy to click for a visitor with Parkinson’s disease or rheumatism.
• Make sure the colour-contrast ratio between text and background is at least 4.5:1 and, for the underlining itself at least 3:1. Googling colour contrast analyser will bring up plenty of free tools and add-ons that will calculate the contrast ratio for you.

To make sure a link will work properly, use an <a> element, with an href containing a url. That way, all devices will know how to operate the link. Keyboard interactions, hover and focus, default styling and feedback

Screen readers announce the content on a website, so there must be actual content to announce, in the form of text: an “accessible name”, as it is called.

There are several ways to add the accessible name to a link, for example:

• Use an image or font icon and add the word “Twitter” to the link. This is also useful for people who don’t know what the icon means. 
• Embed the image in the link – say, the Twitter logo – and give the image the alternative text “Twitter”.
• Give the link its accessible name replaces the announcement of the content (or missing content) inside the link.

To jump to a different point on the same webpage. That’s convenient for the visitor, who can skip large parts of the page and go straight to the content they’re interested in.

But take care to not only the visual but the keyboard focus should move to the destination. Modern browsers do this by default. Older browsers need a tabindex= “-1” on the destination element to receive the focus. The best way to check this is to test it with an actual keyboard.