The WhatsApp Inc. mobile-messaging application WhatsApp is displayed on a Samsung Electronics Co. Galaxy S4 smartphone, left, and an Apple Inc. iPhone in this arranged photograph taken in London, U.K., on Thursday, Feb. 20, 2014. Facebook, the world’s largest social network, agreed to acquire mobile-messaging startup WhatsApp Inc. for as much as $19 billion in cash and stock, seeking to expand its reach among users on mobile devices. Photographer: Chris Ratcliffe/Bloomberg (Chris Ratcliffe/Bloomberg)

WhatsApp’s multibillion-dollar acquisition by Facebook has turned more than a few heads — and not just with the steep price tag.

WhatsApp is known for placing a strong focus on privacy, and co-founder Jan Koum has been vehement about his opposition to advertising in the product. Facebook is sometimes thought to have overstepped users’ expectations — and sometimes even government guidelines — on both points.

Maintaining the same privacy and security standards in WhatsApp is clearly an important point for Koum. Those close to him attribute that focus to his upbringing in Ukraine and fears about something many Americans may now worry about: government surveillance.

When Koum came to the United States as a 16-year-old, he was living on food stamps and looking for an easy way to communicate with his family back home, according to Jim Goetz, a venture capitalist at Sequoia Capital, a firm that invested in WhatsApp.

In building the app, Koum focused heavily on making sure that it was secure and did not collect too much personal information.

“It’s a decidedly contrarian approach shaped by Jan’s experience growing up in a communist country with a secret police,” Goetz wrote on Sequoia ’s Tumblr page. “Jan’s childhood made him appreciate communication that was not bugged or taped.”

Those downloading WhatsApp do grant the program a number of permissions for their phones, including the ability to read their contact lists, read phone status and identity and look at their location information. But the company has said that it does not collect users’ personal information and knows only users’ phone numbers and those of their contacts.

For those who may worry that WhatsApp’s focus on privacy will fall by the wayside now that it has been snapped into the Facebook ecosystem, both companies have been clear that little about WhatsApp is set to change — at least for the foreseeable future.

In remarks Wednesday, Facebook chief executive Mark Zuckerberg made it clear that the company has no plans to put ads in WhatsApp, saying they are not the “right way to mon­etize messaging.”

Koum, for his part, has said that nothing will change for WhatsApp users as a result of the new acquisition.

“You can continue to use WhatsApp no matter where in the world you are, or what smartphone you’re using,” Koum wrote in a post on WhatsApp’s official company blog.

“And you can still count on absolutely no ads interrupting your communication,” he said.

“There would have been no partnership between our two companies if we had to compromise on the core principles that will always define our company, our vision and our product.”