The methodology linked from the article[0] defines it as people who answered "yes" to either of these questions:

> (1) Do you use the internet or email, at least occasionally?

> (2) Do you access the internet on a cell phone, tablet or other mobile handheld device, at least occasionally?

Before mid-2013, the survey used different questions.

[0] https://www.pewresearch.org/wp-content/uploads/2021/03/Non-i...