Covid - Gain of Function Research

 I happened upon a YouTube video today - Thank you YouTube for the link! - concerning a debate that had just taken place in Congress between Senator Rand Paul and the great Wizard of Oz, Doctor Fauci concerning Gain of Function research at the Wuhan virus lab suspected of engineering the Covid-19 virus.

Here's some of that debate:

‘You Do Not Know What You Are Talking About!’: Fauci Lashes Out At Sen. Rand Paul For Suggesting He Lied To Congress

If Fauci the Great wasn't lying to Congress, then I have a couple of questions:

1. What is the correct term for the kind of research Senator Paul was referring to? If it isn't "gain of function research" then please do share with us the proper technical name so we can refer to it without being accused of being clueless.

and...

2. What does the term "gain of function research" actually refer to.

Please, gentlemen, spare us the needless confusion. Why is Doctor Who even testifying if not to give clarity?