What is Impermanent loss?

[notfairchild]

I watched many videos on Impermanent loss but none of them has showed or explained what happens when your take out your liquidity.

Say I provided $2000 worth of liquidity in the pool, $1000 USDT and $1000 worth of ETH, someone takes $100 USDT by giving 0.02 ETH ( $100 ) ETH so what happens then if I un-stake my LP and withdraw, what will I get full $2000 or what?

Thanks in advance