Name	Category	Origin	Purpose	Storage Duration
act	Required	.facebook.com	Used to distinguish between two Facebook sessions for the same user, created at different times.	Session
c_user	Required	.facebook.com	The Facebook user ID of the currently logged-in user.	90 days
fblo_	Required	nerdspot.events	Used to log in users via Facebook.	6 months
fbm_	Required	nerdspot.events	Used to log in users via Facebook.	3 months
user-is-logged-in	Required	nerdspot.events	Saves that the user is/was logged in.	31536000 seconds
LF9x	Required	nerdspot.events	Unique ID that identifies the user's session.	14000 seconds
datr	Marketing	.facebook.com	Used to identify the web browser used to connect to Facebook regardless of the user logged in.	2 years
_fbp	Marketing	.facebook.com	Used by Facebook to display a range of advertising products, such as real-time bids from third party advertisers.	3 months
fr	Marketing	.facebook.com	Used to show and measure ads and improve the relevance of ads (including measurement of conversions). Determines the relevance of ads based on site behavior and/or current search queries.	3 months
sb	Marketing	.facebook.com	Used to show and measure ads and improve the relevance of ads (including measurement of conversions). Determines the relevance of ads based on site behavior and/or current search queries.	2 years
spin	Marketing	.facebook.com	Set by Facebook at login - exact usage unknown.	25 hours
	Marketing	nerdspot.events	Used to collect consent for tracking the user ID in Matomo. No cookie is set.
	Marketing	nerdspot.events	Used to collect consent for tracking the user email in Matomo. No cookie is set.
wd	Statistics	.facebook.com	This cookie stores the dimensions of the browser window and is used by Facebook to optimize the display of the page.	7 days
_GRECAPTCHA	Statistics	https://www.google.com	Cookie set by Google reCAPTCHA to protect the site from spam by bots.	180 days
mtm_consent	Statistics	nerdspot.events	Used to remember that consent was given by the user.	Unlimited
_pk_cvar.*	Statistics	nerdspot.events	Used to temporarily store data for the visit.	30 minutes
_pk_hsr.*	Statistics	nerdspot.events	Used to temporarily store data for the visit.	30 minutes
_pk_id.*	Statistics	nerdspot.events	Used to store details about the user (e.g. a unique visitor ID)	13 months
matomo_ignore	Statistics	stats.pcsg-server.de	Flags the user as ignored from tracking.	Unlimited
_pk_ref.*	Statistics	nerdspot.events	Used to store the attribution information (e.g. the referrer initially used to visit the website).	6 months
_pk_ses.*	Statistics	nerdspot.events	Used to temporarily store data for the visit.	30 minutes
MATOMO_SESSID	Statistics	nerdspot.events	Created when opt-out feature is used. Helps prevent CSRF security issues.	Temporary
_pk_testcookie.*	Statistics	nerdspot.events	Used to check whether the visitor’s browser supports cookies.	1 second
xs	Preferences	.facebook.com	This cookie contains several pieces of information about the user’s session.	3 months

Open Source

Compare early Linux and Android’s staggered launch to see what source availability, licensing and a usable platform each contribute to open source.

Pixel-art bedroom seen from above, with an open beige computer, floppy disks and a circuit notebook beside a glowing CRT

Linux at 35: Inside the First Source Release

The first Linux release offered something more demanding than an installer: a design to inspect. Read the evidence behind its hardware limits, MINIX dependency and later licensing change.

Pixel art of hands holding an upright smartphone in a dark retro bedroom with a glowing CRT, cassettes and a rainy window.

Android at 18: Three Dates That Built a Platform

The SDK, the source code and the first phone did not arrive together. Android’s staggered beginning reveals what it takes to open a platform.