We’ve all been there. You’re scrolling through Facebook and suddenly you see an ad for something so spot on you wonder how on earth they knew you wanted it. Sometimes it feels like Facebook can read our minds, which is great when we’re marketing something and need laser-targeted ads but slightly weird when you’re the user seeing them. So, how do they do it?

As explained in their new ad education portal, Facebook keeps ads “useful and relevant” in four distinct ways:

Activity on Facebook apps and services

Firstly, they analyse your activity across the Facebook family of apps, which includes Messenger, Whatsapp, Instagram and others. It includes things like:

Pages you and your friends like

Information from your Facebook and Instagram profile

Places you check in to using Facebook

Keywords used in your posts

Information shared with a business

When you share information such as your phone number or email address with a business, the business may add it to a customer list that can be matched to your Facebook profile. In particular, Facebook uses data compiled by firms like Experian, Acxiom and Epsilon. These firms build profiles of people over long periods, gathering data from government and public records, consumer contests, warranties and surveys, and private commercial sources. This kind of information can also be used in algorithms that use the information to draw further conclusions, like whether you’re likely to eat organic or enjoy city breaks etc. Sources of this kind of information include:

Loyalty programmes (for example, a supermarket ‘club card’)

Magazine subscriptions

Purchases at retail stores

Location

Facebook use location data to target ads at people who may be close or trying to reach a particular place. They get this type of information from sources such as:

Where you connect to the internet (via yourIP address on computers, tablets and phones)

Where you use your phone (through GPS and location services )

Your location from your Facebook and Instagram profile

Other online activity

And finally, the big vague one. While you’re logged onto Facebook the network can see almost every other website you visit. Use Facebook on your phone? You’re permanently logged in, meaning they have access to everything you browse online on that device. Even when you’re logged off, Facebook knows a lot of your browsing: it’s alerted every time you load a page with a ‘like’ or ‘share’ button, for example. Technologies such as the Facebook pixel allow advertisers (and Facebook too) to track and monitor your behaviour on their site. Business and organisations can try to reach people who have done things such as:

Viewed a web page that uses a Facebook pixel

Downloaded their mobile app

Made a purchase (or simply added a product to a shopping cart)

There’s no denying this kind of data is flawed, as it makes a lot of assumptions. But it’s scarily accurate a lot of the time, making Facebook one of the big advertising giants of our time. Want to find out all the data points Facebook is using to target ads to you? Here’s the full list, courtesy of the Washington Post:

1. Location
2. Age
3. Generation
4. Gender
5. Language
6. Education level
7. Field of study
8. School
9. Ethnic affinity
10. Income and net worth
11. Home ownership and type
12. Home value
13. Property size
14. Square footage of home
15. Year home was built
16. Household composition
17. Users who have an anniversary within 30 days
18. Users who are away from family or hometown
19. Users who are friends with someone who has an anniversary, is newly married or engaged, recently moved, or has an upcoming birthday
20. Users in long-distance relationships
21. Users in new relationships
22. Users who have new jobs
23. Users who are newly engaged
24. Users who are newly married
25. Users who have recently moved
26. Users who have birthdays soon
27. Parents
28. Expectant parents
29. Mothers, divided by “type” (soccer, trendy, etc.)
30. Users who are likely to engage in politics
31. Conservatives and liberals
32. Relationship status
33. Employer
34. Industry
35. Job title
36. Office type
37. Interests
38. Users who own motorcycles
39. Users who plan to buy a car (and what kind/brand of car, and how soon)
40. Users who bought auto parts or accessories recently
41. Users who are likely to need auto parts or services
42. Style and brand of car you drive
43. Year car was bought
44. Age of car
45. How much money user is likely to spend on next car
46. Where user is likely to buy next car
47. How many employees your company has
48. Users who own small businesses
49. Users who work in management or are executives
50. Users who have donated to charity (divided by type)
51. Operating system
52. Users who play canvas games
53. Users who own a gaming console
54. Users who have created a Facebook event
55. Users who have used Facebook Payments
56. Users who have spent more than average on Facebook Payments
57. Users who administer a Facebook page
58. Users who have recently uploaded photos to Facebook
59. Internet browser
60. Email service
61. Early/late adopters of technology
62. Expats (divided by what country they are from originally)
63. Users who belong to a credit union, national bank or regional bank
64. Users who investor (divided by investment type)
65. Number of credit lines
66. Users who are active credit card users
67. Credit card type
68. Users who have a debit card
69. Users who carry a balance on their credit card
70. Users who listen to the radio
71. Preference in TV shows
72. Users who use a mobile device (divided by what brand they use)
73. Internet connection type
74. Users who recently acquired a smartphone or tablet
75. Users who access the Internet through a smartphone or tablet
76. Users who use coupons
77. Types of clothing user’s household buys
78. Time of year user’s household shops most
79. Users who are “heavy” buyers of beer, wine or spirits
80. Users who buy groceries (and what kinds)
81. Users who buy beauty products
82. Users who buy allergy medications, cough/cold medications, pain relief products, and over-the-counter meds
83. Users who spend money on household products
84. Users who spend money on products for kids or pets, and what kinds of pets
85. Users whose household makes more purchases than is average
86. Users who tend to shop online (or off)
87. Types of restaurants user eats at
88. Kinds of stores user shops at
89. Users who are “receptive” to offers from companies offering online auto insurance, higher education or mortgages, and prepaid debit cards/satellite TV
90. Length of time user has lived in house
91. Users who are likely to move soon
92. Users who are interested in the Olympics, fall football, cricket or Ramadan
93. Users who travel frequently, for work or pleasure
94. Users who commute to work
95. Types of vacations user tends to go on
96. Users who recently returned from a trip
97. Users who recently used a travel app
98. Users who participate in a timeshare

Source: Washington Post