What is the meaning of Crackling?

Fat that, after roasting a joint, hardens and crispens

The crispy rind of roast pork.

A crispy, fried skin or rind, especially of pork.

The making of small, sharp cracks or reports, frequently repeated.

Food for dogs, made from the refuse of tallow melting.

Three stripes of velvet worn on the sleeves of students at St John's College, Cambridge.

Sounding with small, sharp cracks or reports, frequently repeated.

present participle and gerund of crackle

Source: wiktionary.org