Obamacare touches just about everyone.

It's not just for the millions of people who have health insurance through the Obamacare exchanges or Medicaid expansion.

Under Obamacare, senior citizens pay less for Medicare coverage and for their prescription drugs. Many people receive free contraceptives, mammograms, colonoscopies and cholesterol tests. And those with pre-existing conditions are no longer turned away.

"The ACA made changes in every part of the health care system," said Larry Levitt, senior vice president at the Kaiser Family Foundation, of the Affordable Care Act. "Virtually everyone has been touched by the ACA."

Some 20 million people have gained coverage under Obamacare. The nation's uninsured rate dropped to a record low 8.6% last year.

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Obamacare remains the law of the land now that the Republican effort to repeal and replace it has been shelved. The Trump administration likely will make some changes to it, and lawmakers may try again to overhaul it.

Here's how sweeping the landmark health care reform law is.

Medicare

Obamacare has meant lower premiums, deductibles and cost-sharing for the 57 million senior citizens and disabled Americans enrolled in the program. It has also reduced how much they have to pay for prescription drugs by slowly eliminating the infamous "donut hole."

The health reform law made many changes to Medicare. It slowed the growth of payment rates to hospitals and other providers, reduced payments to Medicare Advantage plans and improved benefits for enrollees.

As a result, Medicare beneficiaries have to shell out less for premiums, deductibles and co-pays because they are tied to the growth of federal spending on the program. The Obama administration estimated that the typical Medicare beneficiary pays about $700 less in premiums and cost sharing.

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Under Obamacare, Medicare enrollees also receive free preventative benefits, such as screenings for breast and colorectal cancer, heart disease and diabetes.

And Obamacare is closing the gap in Medicare's drug coverage, completely eliminating it by 2020. Senior citizens have to pay more for drugs while they are in the donut hole. For 2017, the gap begins when enrollees and their insurers spend $3,700 for medication and ends after they hit $4,950 in costs. Since Obamacare was passed in 2010, more than 11 million people have saved an average of more than $2,100 a person on prescription drugs, the Obama administration said before leaving office.

But Obamacare does mean higher costs for more affluent beneficiaries. The law froze the threshold for the Medicare premium surcharge at $85,000 for individuals and $170,000 for couples, so more people have become subject to it. The Affordable Care Act also added a premium surcharge on drug coverage for higher-income enrollees.

The Republican health care bill would have left Obamacare's changes to Medicare largely alone. However, House Speaker Paul Ryan has long advocated the overhaul of the government program. It remains to be seen whether Ryan will push for those changes later this year.

Employer-sponsored insurance

Obamacare requires that companies with at least 50 employees provide affordable insurance to their staffers who work more than 30 hours a week.

This mandate didn't have a major impact on the 150 million workers who are insured through their jobs. Most larger employers already offer coverage for full-time workers. However, setting the bar at 30 hours a week prompted some employers to extend coverage to more of their staff, since many companies had considered that threshold to be part-time.

Also, the law allows children to remain on their parents' plans until they turn 26. This has proved to be one of the more popular Obamacare provisions and has helped lower the uninsured rate of this age group.

Workers also no longer have to pay for contraceptives and preventative screenings, such as colonoscopies and mammograms. Obamacare requires these be provided free-of-charge.

Obamacare also prohibits employers from imposing annual or lifetime limits on benefits and caps out-of-pocket spending to $7,150 for single workers in 2017.

Obamacare also had an impact on employees who work at companies with fewer than 50 workers. Insurers can no longer ban workers with pre-existing conditions or ask them to pay more. The law requires plans to cover an array of benefits, including maternity, mental health and prescription drugs. And it limits insurers from charging older workers premiums more than three times those of younger workers.

However, this more comprehensive coverage has come at a price. Many small businesses have seen their premiums spike, forcing some to stop offering health insurance to their workers.

The GOP repeal effort would have eliminated the employer mandate.

Individual market

Obamacare has had the largest impact on the individual market, which was largely unregulated prior to the health reform law.

It requires insurers to cover people with pre-existing conditions and banned them from charging the sick more. The law ended the practice of insurers imposing annual or lifetime caps on benefits, and it also placed limits on annual out-of-pocket spending. It mandates that insurers provide more comprehensive benefits, including medication, maternity and mental health. It prevents insurers from charging women more and restricts premiums for older folks to no more than three times those of young adults.

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Obamacare set up health insurance exchanges to allow Americans to shop for individual policies and created federal subsidies so low- and moderate-income enrollees could buy policies for less than 10% of their income. Another set of subsidies limit the deductibles and co-payments for lower-income policyholders.

Some 12.2 million people signed up for coverage through the Obamacare exchanges for 2017.

About 7 million Americans purchase individual policies outside of the Obamacare exchanges. They cannot apply for subsidies, but receive all of the other benefits.

Not everyone, however, has been happy with the changes Obamacare has brought to the insurance market. Some people are upset that they can no longer buy bare-bones policies, which come with high deductibles and few benefits, but low premiums. And many middle class Americans, particularly those who don't qualify for subsidies, say Obamacare premiums and deductibles are unaffordable.

The House legislation would have made many changes to the individual market. It would have eliminated the individual mandate, allowed insurers to charge older workers more and provide tax credits to help people pay premiums based mainly on age. The bill also would have dropped the requirement that insurers provide comprehensive coverage.

Medicaid

Before Obamacare, most Medicaid enrollees were low-income children, pregnant women, parents, the disabled and the elderly.

The health reform law opened up the program to low-income adults with incomes of up to 138% of the poverty line -- $16,400 for a single person -- in states that opted to expand their Medicaid programs. So far, 31 states, plus the District of Columbia, have done so. Some 11 million Americans have gained coverage under this provision.

Under the program, the federal government paid 100% of the costs of the expansion population for the first three years and is slowly lowering the reimbursement rate to 90%.

House Republicans were looking to make big changes to Medicaid. The bill would have not only ended the enhanced funding for Medicaid expansion, but would have curtailed federal support for the entire program.

Uninsured

Obamacare required that all Americans obtain insurance or pay a penalty, which this year hit $695 per adult or 2.5% of household income, whichever is greater.

That mandate remains but the Trump administration is weakening it.

The IRS last month quietly reversed a decision to reject tax returns that fail to indicate whether filers had health insurance, received an exemption or paid the penalty. While this has always been key to enforcing the individual mandate, the IRS had been processing returns without this information under the Obama administration.

The IRS attributed the reversal to Trump's executive order that directed agencies to reduce the potential financial burden on Americans.

A version of this story originally ran on January 2, 2017.