Platform edges are hard to locate. Power-laden like a city-state, vertiginous like a ten-metre diving platform, lifted-up like a concert stage, replete with technicalities like a geometrical proof, and as niche-rich as coastal rocks, platform edges run between inside and outside, core and periphery, on and off.

It may be that platform edges run along tangled lines of code and devices, through interfaces, networks, sensors, chips and screens. Inhabited in practice yet difficult to perceive or untangle, people step into these entanglements every time they open and close documents across different devices and platforms. Sometimes not knowing where the document is stored, they pause to ask: ‘Where is that file?’ They negotiate uncertain boundaries and thresholds between what belongs to them and what belongs to others, what is part of their work and what is not, or where their work takes place given the complete mixing of platforms into work, education, home life and government. Their work, their time with family and friends, their finances, health, education and leisure, increasingly run into platform edges guarded by requests for user names and authentication or ‘use Google/Facebook/Apple to login’ requests. They encounter limits in storage on their devices or in cloud data stores and wonder whether to copy everything somewhere else, or buy more space. They lose or find themselves using apps chosen from tens of thousands on offer in app stores such as GooglePlay and Apple Corporation's App Store.