Let's talk about with WCAG Principle 3, Understandable.

The first step to making our web content understandable is making it readable.

At its most basic level,

this means making the default language of our content identifiable.

This is a low hanging fruit.

We can accomplish it by including the lang attribute in our HTML element.

A predictable web page doesn't do things that the user hasn't asked it to do.

Changing focus or

the settings of the UI component shouldn't trigger a change of context.

What's a change of context you ask?

This is a great time to point out that the WCAG working group is pretty self-aware.

They know they've used terms that might not be familiar or

make sense to regular people in this context.

Knowing that, they've created a glossary.

You can click on many of the terms you'll find throughout the guidelines to see

an explanation.

In this case, we'll click on change of context.

This is great because not only does it expand on the term itself,

but it gives us an example.

So now we now that success criteria 3.2.1 and

3.2.2 are saying we should never trigger things like pop-up windows or

switch to a different page just because an element has received focus or

UI settings have changed.

Taking the time to discover the meaning of terms you don't understand will make it

much easier to gauge the excessive ability of your work in a long run.

The last guideline governed by the understandable principle has to do with

input elements.

Whatever the user needs to do to fill out our forms should be crystal clear.

Provide sufficient instructions and label all of your input elements.

Any error we detect should be communicated to the user so that they can fix it.

Have you ever filled out a form and had your input rejected but

couldn't tell what was wrong?

This kind of issue could keep a new user from signing up for your service, or

a customer from buying your product.