2 Copyright © 2016-2018 Soren Stoutner <soren@stoutner.com>.
4 This file is part of Privacy Browser <https://www.stoutner.com/privacy-browser>.
6 Privacy Browser is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Privacy Browser is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with Privacy Browser. If not, see <http://www.gnu.org/licenses/>. -->
21 <meta charset="UTF-8">
23 <link rel="stylesheet" href="../css/dark_theme.css">
27 <h3><img class="title" src="../shared_images/cookie_blue_dark.png"> First-Party Cookies</h3>
29 <p>First-party cookies are set by the website in the URL bar at the top of the page.</p>
31 <p>From the early days of the internet, it became obvious that it would be advantageous for websites to be able to store
32 information on a computer for future access. For example, a website that displays weather information could ask the
33 user for a zip code, and then store it in a cookie. The next time the user visited the website, weather information
34 would automatically load for that zip code, without the user having to enter the zip code, and without the need for
35 the user to create an account on the website (which would be overkill for such a simple task).</p>
37 <p>Like everything else on the web, clever people figured out all types of ways to abuse cookies to do things that users
38 would not approve of if they knew they were happening. For example, a website can set a cookie with a unique serial
39 number on a device. Then, every time a user visits the website on that device, it can be linked to a unique profile
40 the server maintains for that serial number, even if the device connects from different IP addresses, as cell phones often do.</p>
42 <p>Many websites with logins require first-party cookies to be enabled for a user to stay logged in. Cookies aren’t the only way
43 a website can maintain a user logged in as they move from page to page on the site, but if a particular website has chosen to
44 implement logins in that way, enabling first-party cookies on that site will be the only way to use the functionality.</p>
46 <p>If first-party cookies are enabled but JavaScript is disabled, the privacy icon will be yellow <img class="inline" src="../shared_images/warning.png">
50 <h3><img class="title" src="../shared_images/cookie_blue_dark.png"> Third-Party Cookies</h3>
52 <p>Third-party cookies are set by portions of a website that are loaded from servers different from the URL at the top of the page.
53 For example, most website that have advertisements load them from a third-party ad broker, like Google’s
54 <a href="https://www.google.com/adsense/start/#?modal_active=none">Ad Sense</a>. Every time the website loads, it requests the ad
55 broker to display an ad. The ad broker analyzes any information they may have about the user, looks at the current
56 rate advertisers are willing to pay for their ads, and selects the one to display. The section of the website that displays
57 the ads is loaded from the third-party broker’s server instead of the main server.</p>
59 <p>Because most of the advertisements on the internet are processed by only a few brokers, it didn’t take long for them to realize
60 that they could set a tracking cookie on the user’s device and know every place that user goes. Every time an ad loads from a broker,
61 the first thing it does it check to see if if the device already has a unique serial number in a tracking cookie. If it does, it looks up
62 the profile for that serial number and makes a note of the new site. This is why a user can do a search on one website for a
63 product they typically don’t look for, like walnuts, and then suddenly start seeing advertisements for walnuts on every
64 website they visit.</p>
66 <p>In addition to ad brokers, social media sites discovered they could get in on the action. A few years ago, the major social media sites
67 like Facebook and Twitter convinced a large number of websites that it would be in there best interest to place little social media
68 icons on their pages. These are not just images. They contain <a href="https://developers.facebook.com/docs/plugins/like-button/">embedded code</a> that
69 links back to the social media site, and, among other things, loads a third-party cookie on the device. These cookies are placed even if the user does
70 not have an account with the social media platform. Over time, companies like Facebook (which also runs an ad network) have built up quite a large number
71 of detailed profiles about people who have <a href="http://www.theverge.com/2016/5/27/11795248/facebook-ad-network-non-users-cookies-plug-ins">never even
72 created an account on their site</a>.</p>
74 <p>There is almost no good reason to ever enable third-party cookies. On devices with Android KitKat or older (version <= 4.4.4 or API <= 20), WebView
75 does not <a href="https://developer.android.com/reference/android/webkit/CookieManager.html#setAcceptThirdPartyCookies(android.webkit.WebView, boolean)">differentiate
76 between first-party and third-party cookies</a>. Thus, enabling first-party cookies will also enable third-party cookies.</p>
79 <h3><img class="title" src="../shared_images/web_blue_dark.png"> DOM Storage</h3>
81 <p>Document Object Model storage, also known as web storage, is like cookies on steroids. Whereas the maximum combined storage size for all cookies from
82 a single URL is 4 kilobytes, DOM storage can hold <a href="https://en.wikipedia.org/wiki/Web_storage#Storage_size">megabytes per site</a>.
83 Because DOM storage uses JavaScript to read and write data, enabling it will do nothing unless JavaScript is also enabled.</p>
86 <h3><img class="title" src="../shared_images/subtitles_blue_dark.png"> Form Data</h3>
88 <p>Form data contains information typed into web forms, like user names, addresses, phone numbers, etc., and lists them in a drop-down box on future visits.
89 Unlike the other forms of local storage, form data is not sent to the web server without specific user interaction.</p>