It's not just Granny Squares, it's a life skill . . .
It involves lots' of patience, while knotting yarn, string, thread, or even metal wire using a small hook. Unlike knitting; crochet only uses a single hook. Crochet can be done freeform or following a pattern to create a broad range of items such as blankets, fashion accessories, toys, and even home goods. There are various techniques originating from many different regions that give unique styles.
Amigurumi came from Japan, a popular style of micro crochet used to make beloved toys and plushies.
Irish lace crochet which you see commonly on lace curtains, table cloths, and other fine garments.
Tunisian crochet replicates a knit look that orginated in France and can be seen on many tapestries and murals.
Mosaic crochet is commonly used to create intricate color change patterns and textures.