Final answer:
Tight gas is a type of natural gas found in rock with very low permeability, requiring hydraulic fracturing to extract it due to the inability of the gas to flow freely through the rock.
Step-by-step explanation:
Tight gas is natural gas that is trapped in a rock formation with low permeability, which is typically less than 0.1 millidarcies (mD). Due to the low permeability of the rock, natural gas does not flow easily, and extraction requires advanced techniques such as hydraulic fracturing (fracking) to create fractures in the rock that allow the gas to flow. This method is similar to the one used for extracting 'tight oil' from impermeable rock formations.