~ in r Page 190

The tilde (~) in R is the little workhorse that builds formulas: y ~ x + z tells models and functions how variables relate.

It powers stats functions (lm, glm), graphics (lattice), and tools like aggregate and reshape, where the left side is the outcome and the right side holds predictors or grouping.

In the tidyverse, ~ also moonlights as a shorthand for anonymous functions with purrr: map(x, ~ .x + 1) — neat, quick, and mildly addictive.

So: ~ makes formulas, guides modelling, and doubles as a tiny function factory; not bad for a squiggle.