Handing over your personal data is now often the cost of romance, as online dating services and apps vacuum up information about their users’ lifestyle and preferences.

Why it matters: Dating app users provide sensitive information like drug usage habits and sexual preferences in hopes of finding a romantic match. How online dating services use and share that data worries users,according to an Axios-SurveyMonkey poll, but the services nonetheless have become a central part of the modern social scene.

What they know:

• Everything you put on your profile, including drug use and health status. Web trackers can examine your behavior on a page and how you answer key personal questions. JDate and Christian Mingle, for example, both use a tracker called Hotjar that creates an aggregate heat map of where on a web page users are clicking and scrolling.
• Every time you swipe right or click on a profile. “These can be very revealing things about someone, everything from what your kinks are to what your favorite foods are to what sort of associations you might be a part of or what communities you affiliate with,” says Shahid Buttar, director of grassroots advocacy for the Electronic Frontier Foundation.
• How you're talking to other people. A reporter for the Guardian recently requested her data from Tinder and received hundreds of pages of data including information about her conversations with matches.
• Where you are. Location data is a core part of apps like Tinder. “Beyond telling an advertiser where someone might physically be at a given time, geolocation information can provide insights into a person’s preferences, such as the stores and venues they frequent and whether or not they live in an affluent neighborhood,” says former FTC chief technologist Ashkan Soltani.

The details: Popular dating websites broadly collect information on their users for advertising purposes from the minute they first log on to the site, according to an analysis by the online privacy company Ghostery of the websites for OkCupid, Match.com, Plenty of Fish, Christian Mingle, JDate and eHarmony. (Ghostery, which performed the analysis for Axios, lets people block ad trackers as they browse the web.)

• Popular services broadly track their users while they search for potential matches and view profiles. OkCupid runs 10 advertising trackers during the search and profile stages of using its site, Ghostery found, while Match.com runs 63 — far exceeding the number of trackers installed by other services. The number and types of trackers can vary between sessions.
• The trackers can collect profile information. Match.com runs 52 ad trackers as users set up their profiles, Plenty of Fish runs 21, OkCupid runs 24, eHarmony runs 16, JDate runs 10 and Christian Mingle runs nine.
• The trackers could pick up where users click or where they look, says Ghostery product analyst Molly Hanson, but it's difficult to know for sure. "If you're self-identifying as a 35 year-old male who makes X amount of money and lives in this area, I think there's a wealth of personal information that should be pretty easy to capture in a cookie and then send to your servers and package it and add it to a user profile," says Jeremy Tillman, the company's director of product management.

Many of these trackers come from third parties. OkCupid installed seven ad trackers to watch users as they set up their profiles. Another 11 came from third parties at the time Ghostery ran its analysis. Trackers include data companies that often sell data to other companies looking to target people, Hanson says.

Match Group owns a number of dating services, including Tinder and OkCupid. The privacy policies say user data can be shared with other Match Group-owned services.

What they’re saying: A spokesperson for Match Group says in a statement said that data collected by its companies "enables us to make product improvements, deliver relevant advertisements and continually innovate and optimize the user experience."

"Data collected by ad trackers and third parties is 100% anonymized," the spokesperson says. "Our portfolio of companies never share personally identifiable information with third parties for any purpose."

• The primary business model of the industry is still based around subscriptions rather than targeting ads based on personal data, notes Eric Silverberg, the CEO of gay dating app Scruff.
• "I would argue that the incentive to share information is actually lower for dating businesses than it is for media businesses and news sites. ... We have subscription services and our members pay us for the services we provide and the communities we create,” he says.

Why you’ll hear about this again: Researchers routinely uncover security risks related to dating apps.

• A security firm recently claimed to have found security flaws in Tinder.
• The 2015 Ashley Madison hack resulted in the personal data of users of the site, which purported to facilitate infidelity, being exposed.
• The FTC last week warned of dating app scams.