Using Abbreviations on A Web Page
In countless situations we use abbreviations, some are more, some are less obvious or commonly understood.
When it comes to the internet, it is a good idea to provide the full meaning of an abbreviation. But in reality, it is not that clear cut. I will provide a couple of ideas on when and how to provide the full phrases.
WCAG 2.0, under 3.1.4 requires to identify the meaning of abbreviations. The reason why it is included is because it is often not obvious what abbreviations stand for, and also, it greatly helps people with cognitive disabilities.
WCAG under the Sufficient techniques requires to do it at least for the first time. This is satisfactory in most situations. For example, on this site I talk a lot about the JAWS screen reader. Given the context, people who read these articles are most likely familiar with what JAWS is, and it would be unnecessary to expand it to "Job Access with Speech" every single time I mention "JAWS". I would even go further, if the article is about testing with JAWS, people are there to get additional JAWS related information, it might not even be necessary to expand the meaning, I did it, regardless.
When the abbreviation may not be obvious for the first time, it is a great idea expand it at least for the first time, maybe even a second time, especially if you are using lot's of abbreviations within a page. Depending on the complexity of the abbreviation, it may be hard to remember the entire phrase, let alone several phrases, so it would be recommended to repeat the expanded text more times. An example would be the CRPD, The Convention on The Rights of Persons with Disabilities. This is a mouthful and it is more likely not be remembered if somebody is reading it for the first time.
Once decide where to display the full meaning, it is time to decide how. There are several alternatives.
The easiest way to do it is by using parentheses. For example: CRPD (Convention on The Rights of Persons with Disabilities). This is very common, and it is hard to miss.
The problem with the abbr tag is that not all browsers support it, though screen readers in general understand it's use. The meanings are not only for screen reader users, though.
Another alternative is to use a glossary, where you create a link to a page which contains the meaning, and necessary definitions. This becomes problematic because it breaks the flow of the reading, however, this way you can provide more information. These days, however, when people see a link, they don't automatically associate it to a glossary, rather, with related content, and they might not think about following your link.
There isn't a prescribed solution, use the one that fits your page best, or a combination of the above.