Glue or caulking sticks are put in the chamber, where they are melted by heat and released through the nozzle. The adhesive cures by cooling. Cordless models are also available.
Some models require the operator to maintain pressure on the glue stick with the thumb. Others are self-feeding. The trigger mechanism on some models closes the nozzle to prevent dripping.
There are a variety of glues available—both with a gun and in replacement packages including heavy-duty types for wood joints requiring about 60 seconds drying time and lightweight for paper, etc., with shorter drying time.