As the summer dawns, we look back on the first six months of the year's biggest stories – from population health to ICD-10, meaningful use to privacy and security – that had Healthcare IT News readers clicking, tweeting, liking, sharing and commenting.

1. Entering a new era of population health
With health IT having been embraced in earnest these the past fews years, now it's time to actually put that technology to work. This story explored the vast potential for pop health improvement as patient engagement takes hold and providers make smarter use of data exchange and analytics. A follow-up story, "What to look for in population health at HIMSS15," was almost as popular.

2. 10 tech trends to watch for in 2015
January look-ahead lists are perennially popular, and this one was no exception. Six months into the year, how are ECRI's predictions – from 3D printing to fitness devices –  playing out? At least one ("Google Glass: Dead for consumers but maybe not for healthcare") has already come true.

3. 15 interoperability geeks to watch
From federal policy to nuts-and-bolts standards, ONC to HL7, Bernie Monegain's slideshow put the spotlight on some of the thinkers, makers and doers charting a forward course for one of the most complex, vexing – and all-important – projects in health IT: enabling smooth and widespread data liquidity.

4. Mayo Clinic moves to Epic
When one of the most respected health systems in the country decided to make the switch to one of the largest electronic health record vendors – a multi-year, multi-million-dollar implementation aimed at the next "several decades" of care delivery – people paid attention. Our follow-up interview with Chief Information Officer Cris Ross, "Mayo Clinic CIO explains switch from Cerner to Epic," was also widely-read.

5. 3 ways Congress could still kill ICD-10
Now less than three months away from the Oct. 1, 2015 compliance deadline, ICD-10 still looks (knock wood!) to be on course, after many years of stalling and delays. In April, as some folks on Capitol Hill started making noise about more disruption, Tom Sullivan took a look a some ways mischief could be made.

6. Epic-Cerner competition heats up
The battle for public approval may not be quite as intense (or fizzy) as the legendary Cola Wars of the 1980s, but the jostling for position between the "Coke and Pepsi of EHRs" still has big stakes for the healthcare industry. A February market research study from KLAS found that "the competition between Epic and Cerner is closer than it has been in years past as customers determine their future purchasing plans."

7. Slideshow: 10 biggest health data breaches
At this week's Healthcare IT News Health Privacy Forum, a new HIMSS survey revealed that two-thirds of health organizations have experienced a "significant security incident" in the recent past. Breaches and "incidents" aren't necessarily the same thing, but since 2014 Erin McCann's list has been keeping track of some of some of the most serious instances of data compromise. The year kicked off, of course, with one of the biggest ever: a hack targeted at Anthem that affected the health data of some 80 million people.

8. Stage 3 meaningful use proposed rule and certification criteria released
Even as many providers continued to struggle with Stage 2, CMS and ONC are charging ahead with Stage 3 mandates, promising "flexibility" and an effort to "simplify" the federal program. As usual, the rules dropped late on a Friday afternoon. A subsequent post from Micky Tripathi and John Halamka, MD, unpacking "The good, the bad and the ugly of Stage 3 MU," was also very popular.

9. CMS lays out vision for Stage 3 meaningful use
Speaking at HIMSS15 in Chicago, Rob Anthony, deputy director of the quality measurement and health assessment group at the Centers for Medicare & Medicaid Services, explained what CMS is after with the new rules: a focus on "areas that were priorities for us as an agency, but also for us as healthcare providers and consumers: promoting health information exchange and focusing on improved outcomes."

10. Epic trades jabs with CommonWell Health Alliance
Testifying before the Senate in March, Epic's head of interoperability took aim at rival vendor group CommonWell Health Alliance, accusing them bad faith and "lack of transparency." CommonWell, whose members include competitors such as Allscripts and athenahealth, fired back – as did individual members: The Epic comments were a "slap in the face," according to Cerner, which reemphasized its commitment to CommonWell "as a practical, market-led way to achieve meaningful interoperability."