UPDATE: Since writing this post in August 2017, several important changes have taken place in the laws regarding ADA compliance for websites. On December 26, 2017, the Department of Justice announced that they have withdrawn the Obama-era Advance Notice of Proposed Rulemaking mentioned in this article which intended to require ADA website compliance. The DOJ’s withdrawal announcement stated, “The Department will continue to assess whether specific technical standards are necessary and appropriate to assist covered entities with complying with the ADA.”
Nice Article! It is very important to work under guidelines if you don’t want to get sued and don’t want to pay the penalties. But more importantly it is better to give each user hassle free user experience over your website. Being ADA Compliant means your website works well for people with disabilities and they can easily access and navigate your website.
...the full and equal enjoyment of the goods, services, facilities, or accommodations of any place of "public accommodation" by any person who owns, leases, or operates a place of public accommodation. Public accommodations include most places of lodging (such as inns and hotels), recreation, transportation, education, and dining, along with stores, care providers, and places of public displays.
The U.S. Department of Transportation enforces regulations governing transit, which includes ensuring that recipients of federal aid and state and local entities responsible for roadways and pedestrian facilities do not discriminate on the basis of disability in highway transportation programs or activities. The department also issues guidance to transit agencies on how to comply with the ADA to ensure that public transit vehicles and facilities are accessible.
Signed in 1990 at a time that most people hadn’t even used the Internet, the Americans with Disabilities Act does not explicitly regulate how websites need to follow nondiscrimination requirements. We now know that using the Internet is one of the most important ways for people with disabilities to fulfill their needs and desires. For many people with disabilities, especially impairments to sight and motion, visiting a store or other physical location can be a challenging experience. Online shopping, for example, allows people with disabilities to make the purchases they need easily and securely within the comfort of their own homes.

The Department of Justice may file lawsuits in federal court to enforce the ADA Compliance, and courts may order compensatory damages and back pay to remedy discrimination if the Department prevails. Under title III, the Department of Justice may also obtain civil penalties of up to $55,000 for the first violation and $110,000 for any subsequent violation of ADA Compliance.

ADA disabilities include both mental and physical medical conditions. A condition does not need to be severe or permanent to be a disability.[6] Equal Employment Opportunity Commission regulations provide a list of conditions that should easily be concluded to be disabilities: deafness, blindness, an intellectual disability (formerly termed mental retardation), partially or completely missing limbs or mobility impairments requiring the use of a wheelchair, autism, cancer, cerebral palsy, diabetes, epilepsy, Human Immunodeficiency Virus (HIV) infection, multiple sclerosis, muscular dystrophy, major depressive disorder, bipolar disorder, post-traumatic stress disorder, obsessive compulsive disorder, and schizophrenia.[7] Other mental or physical health conditions also may be disabilities, depending on what the individual's symptoms would be in the absence of "mitigating measures" (medication, therapy, assistive devices, or other means of restoring function), during an "active episode" of the condition (if the condition is episodic).[7]

This is particularly important when working for a government agency or government contractor, as these organizations must follow web accessibility guidelines under Section 508 of the Workforce Rehabilitation Act of 1973. Although ADA and Section 508 compliance are different, the published checklist for Section 508 compliance offers insight into ways to make websites accessible for people with disabilities, and thereby work toward ADA compliance.
The 2014 case involving Peapod, an online grocery retailer emphasizes that being ADA compliant goes beyond your website. The settlement required Peapod to make its mobile applications accessible by March 2015 and its website accessible by September 2015. Since mobile apps are fast becoming the preferred method of online shopping, e-commerce sites must focus on app accessibility too. 
This is an article that most other website developers probably don’t want you to read. The reason is that most other web designers basically like to think of themselves as all-powerful wizards with magical powers. And they use complex technical jargon and terminology to intimidate and mystify their clients into thinking that what they do is more complex than it is.
The Americans with Disabilities Act (ADA) was first passed in 1990. Twenty years later, the US Department of Justice released an update called the 2010 ADA Standards for Accessible Design. These standards cover the design of physical spaces and have been interpreted to include web locations as well, so it can be difficult for the would-be accessible website designer to use them.
Talk to your web designer about other techniques that will make your site more user-friendly for people with disabilities. Worried that’s not in your budget? Consider the fact that DOJ fines start at $75,000. And it's still yet to be determined if a non-compliant website is liable for one fine or will be charge per page for each violation. As the recent lawsuits illustrate, though, settlements quickly add up into the millions.

Courts have taken essentially the following position on the issue of whether websites are places of public accommodation: Website accessibility fulfills the spirit of the ADA by lowering the barriers for people with disabilities to participate in business and commerce. As such, commercial websites need to comply with ADA regulations. Judges have reached this conclusion in several high-profile cases, such as the National Federation of the Blind’s lawsuit against the Scribd digital library. As a result of this case, Scribd agreed to redesign its website to work with screen reader software by the end of 2017.

The Federal Communications Commission (FCC) enforces regulations covering telecommunication services. Title IV of the ADA covers telephone and television access for people with hearing and speech disabilities. It requires telephone and Internet companies to provide a nationwide system of telecommunications relay services that allow people with hearing and speech disabilities to communicate over the telephone.
The attorneys' fees provision of Title III does provide incentive for lawyers to specialize and engage in serial ADA litigation, but a disabled plaintiff does not obtain financial reward from attorneys' fees unless they act as their own attorney, or as mentioned above, a disabled plaintiff resides in a state that provides for minimum compensation and court fees in lawsuits. Moreover, there may be a benefit to these "private attorneys general" who identify and compel the correction of illegal conditions: they may increase the number of public accommodations accessible to persons with disabilities. "Civil rights law depends heavily on private enforcement. Moreover, the inclusion of penalties and damages is the driving force that facilitates voluntary compliance with the ADA."[56] Courts have noted:
The World Wide Web Consortium (W3C) established the main international standards and accessibility for the World Wide Web. The WCAG is created by the W3C to provide a standard for web content accessibility that can be shared around the world. The WCAG is meant to accompany organizations as a sort of blueprint on how to make their websites ADA compliant.
Access Now v. Southwest Airlines was a case where the District Court decided that the website of Southwest Airlines was not in violation of the Americans with Disabilities Act, because the ADA is concerned with things with a physical existence and thus cannot be applied to cyberspace. Judge Patricia A. Seitz found that the "virtual ticket counter" of the website was a virtual construct, and hence not a "public place of accommodation." As such, "To expand the ADA to cover 'virtual' spaces would be to create new rights without well-defined standards."[76]
The idea of federal legislation enhancing and extending civil rights legislation to millions of Americans with disabilities gained bipartisan support in late 1988 and early 1989. In early 1989 both Congress and the newly-inaugurated Bush White House worked separately, then jointly, to write legislation capable of expanding civil rights without imposing undue harm or costs on those already in compliance with existing rules and laws.[27]
Since March 15, 2012, ADA compliance with the 2010 Standards will be required for new construction and alterations. In the period between September 15, 2010 and March 15, 2012, covered entities may choose between the 1991 Standards ADA Compliance (without the elevator exemption for Title II facilities), the Uniform Federal Accessibility Standards (Title II facilities only), and the 2010 Standards ADA Compliance.