What is a fifth-generation fighter aircraft?

Any conversation about Australia
Any conversation about Australia's commitment to the F-35 Joint Strike Fighter refers to it as a fifth-generation fighter aircraft. But what exactly is a fifth-generation aircraft, and why is it important?

Fifth-Generation Air Combat

Japan's Scraps Domestic Development of 5th Generation Stealth Fighter Jet – The Diplomat

tilstrækkelig Havanemone Sovereign 5 generation fighter jet overskud ønskelig bibliotekar

Japan Needs More Fifth-Generation Jets

The F-35 JSF: what is a fifth-generation fighter aircraft?

Fifth generation fighter jets - A Chinese, Russian, Indian and US arms race.

Fifth-generation fighter - Wikipedia

Su-57 fifth-generation fighter jets successfully tested in Syria - Military & Defense - TASS

What are 5th generation fighter jets? Why does India need them? – Firstpost