post double crochet

Dear users, dear authors,
What is post double crochet, and what is it used for?

There are front and back post double crochets (you can look up the explanation).
These are often used to add texture to a crochet piece or to create certain types of cable patterns or other patterns, such as checkered designs. For example, a checkered pattern might alternate 5 front post double crochets and 5 back post double crochets.
I often use them as a cuff finish on garments. In knitting, they’re like knit and purl stitches, so to speak.
I can’t really explain it very well right now.