The quantified self is a cultural phenomenon of self-tracking, with technology, adopted by a community of users and makers of self-tracking tools, who share an interest in “self-knowledge through numbers”.
Quantified self, overlaps with the practice of lifelogging and other trends that incorporate technology and data acquisition into daily life, with the goal of improving physical, mental, and emotional performance.
To quote some of my preferred authors:
A few years ago, when I met the movement for the first time, I knew that all my decisions had to be driven by numbers, not by opinions. At the same time, my practice to keep a diary was integrated with daily journaling, while I was storing not only biometric data but also creative and working performances and mental and emotional values.
I started to build some devices that allowed me to acquire, store, and analyze my personal and working performances. At the same time, I went deep into the design of frictionless interfaces to eliminate the stress of data collection.
You can read more about it in the “Frictionless and tangible user interfaces” and “Quantified-Self” section of my blog.