President George H.W. Bush signed the Americans with Disabilities Act into law July 26, 1990. The ADA prohibits discrimination of people with disabilities and guarantees the same opportunities as everyone else. These opportunities include employment possibilities, purchasing of goods and services and the ability to participate in State and local government programs. 

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 guidelines provide the foundation that organizations need to achieve digital accessibility best approaches, however they are not exhaustive. They do not provide direction for all of the accessibility challenges that people with disabilities face. They also fail to provide detailed technical instructions. With these limitations in mind, there is a ray of hope.
Predictable: Websites should operate in ways that are familiar and predictable. When a new page element is in focus, the website should not initiate a change of context such as opening a new window or going to a new page. In addition, the website should warn of user-initiated changes of context ahead of time, for instance through the use of a submit button. Navigation and labeling should remain consistent between different pages.
Until the ADA is updated to address the special case of website accessibility, or the Department of Justice releases its website accessibility regulations, complying with WCAG 2.0 Level AA is the best way to ensure that people with disabilities have equal access to your website. The overview below is a great starting point about meeting the WCAG 2.0 Level AA recommendations.
I own a medical practice in California with 5 employees. Since I have under 15 employees am I exempt from needing to have my website comply with the ADA? I know that my physical practice is exempt from ADA policies regarding employment (under 15) but I don’t know if that extends to websites. My website is not an important part of my practice and I don’t really want to sink any funds into it if I don’t need to.

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. 
Accessible Poetry adds a floating button that, when clicked, exposes a toolbar to allow for font and contrast changes. You can also zoom in and out of the page, along with mark links and disable onscreen flashes. But the star of the show is its ALT Platform area inside the WordPress Dashboard. This screen will list any images uploaded to your site that don’t have an ALT tag assigned. Even better, you can set a tag for each image directly from this listing.
In addition, aids and services include a wide variety of technologies including 1) assistive listening systems and devices; 2) open captioning, closed captioning, real-time captioning, and closed caption decoders and devices; 3) telephone handset amplifiers, hearing-aid compatible telephones, text telephones (TTYs) , videophones, captioned telephones, and other voice, text, and video-based telecommunications products; 4) videotext displays; 5) screen reader software, magnification software, and optical readers; 6) video description and secondary auditory programming (SAP) devices that pick up video-described audio feeds for television programs; 7) accessibility features in electronic documents and other electronic and information technology that is accessible (either independently or through assistive technology such as screen readers) .
This guidance document is not intended to be a final agency action, has no legally binding effect, and may be rescinded or modified in the Department's complete discretion, in accordance with applicable laws. The Department's guidance documents, including this guidance, do not establish legally enforceable responsibilities beyond what is required by the terms of the applicable statutes, regulations, or binding judicial precedent.