WCAG guidelines break accessibility issues down into three levels. Level A issues are the most urgent and include problems that can severely limit a disabled visitor’s ability to navigate or use the website. Level AA issues tend to be more rooted in functionality, addressing areas where improvement is needed to give disabled users the full experience of a site. (Level AA is considered the target standard for most commercial websites.) Level AAA issues are the highest standard, fine-tuning and expanding on issues identified as Level A and AA. While it is an excellent goal, full Level AAA compliance is likely beyond the reach of most websites.

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Level AA is a little more significant, and makes sites accessible to people with a wider range of disabilities, including the most common barriers to use. It won't impact the look and feel of the site as much as Level AAA compliance, though it does include guidance on color contrast and error identification. Most businesses should be aiming for Level AA conformity, and it appears to reflect the level of accessibility the DOJ expects. 
HTML tags – specific instructions understood by a web browser or screen reader. One type of HTML tag, called an “alt” tag (short for “alternative text”), is used to provide brief text descriptions of images that screen readers can understand and speak. Another type of HTML tag, called a “longdesc” tag (short for “long description”), is used to provide long text descriptions that can be spoken by screen readers.
Creating a more operable and navigable website will ultimately benefit all users while still meeting WCAG guidelines. Making your web pages easier to comprehend will allow everyone - disabled or non - to find what they’re looking for quickly. If you decide to follow the guidelines, your website will likely convert more leads across the board because users will trust that they can always easily find the content they need.
People with disabilities may interact with websites and online reservation systems differently than people not affected by disabilities. All types of disabilities need to be considered when setting up your website such as: visual impairments (blindness, low vision, color blindness), hearing impairments, physical disabilities, speech disabilities, cognitive disabilities, and multiple disabilities. Age-related disabilities such as arthritis, hearing loss, and vision loss should also be factored in when making your website ADA compliant.
Jeremy I am an artist and designer. The business I would like to have a website for is painting pet portraits. I also paint them with their owners, kids, etc. The reservations I have about the (template choice) website plans is that none of the templates I have seen show what I do well enough. Is there a site where I can setup or design my own homepage image without using a prescribed template?
The gray area is a matter of scale and purpose. If you have a small business which serves as specific market it's a good idea to make the site as user and disability friendly as possible. If, however, your market serves segments with a likeliness to have various handicaps or disabilities you should address that with an ADA Compliance review of the site. Also consider the scale and purpose of an organization. Publicly traded large businesses need to concern themselves more than a single location family owned retailer and if someone sues your flower shop because the text was too small or didn't have "image alt tags" causing them distress... That's pretty frivolous and would likely not stand.
Additionally, in February 2018, Congress passed the ADA Education and Reform Act, a bill designed to make it harder for disabled Americans to sue businesses for discrimination. Republican lawmakers who wrote and passed the bill argue that the law will help curb “frivolous” lawsuits, while opponents have argued that this law will gut the ADA, essentially giving businesses little reason to follow the ADA guidelines at all.
The ADA itself holds different organizations to more/less stringent standards based on a host of factors, government funding being a major one. Government agencies themselves are usually held to the most severe standards. That said, while ADA has adopted WCAG as the defacto standard, from what I’ve seen it appears they’re going with AA compliance as the most reliable one. That said, we’ve done work with some organizations who’ve chosen to comply with AAA in an effort to be as buttoned up as possible from an accessibility and experiential perspective. We’ve also worked with some who have tighter budgers and aim for level A compliance and have a more “react and repair” mindset when they discover anything in their site that is giving someone hardship from an accessibilirt standpoint.
For federal institutions, Section 508 makes it very clear that all federal-related websites must be accessible to all individuals, with and without disabilities. For private commercial websites, the Department of Justice (DOJ), which enforces the ADA, has made it clear that it interprets the ADA as applicable to websites. In 2010, the DOJ issued an Advanced Notice of Proposed Rulemaking to specifically ensure all websites, public and private, are subject to ADA compliance. The DOJ’s proposed amendments to the ADA were initially expected in Spring of 2016 but have now been pushed back to 2018.

Most recently, however, pizza chain Domino's has been brought under suit for their website not being accessible for specialty ordering. The U.S. Supreme Court refused to review the case, instead upholding the decision of the 9th U.S. Circuit Court of Appeals who said the “alleged inaccessibility of Domino’s website and app impedes access to the goods and services of its physical pizza franchises—which are places of public accommodation.”