We've come a long way from the classic image of stock trading.

There are still men in loud jackets here on Wall Street.

Now that you don't have to be a trader to trade stocks, you could do it right on your phone through APS like Robin Hood.

Robin Hood let everyday people buy and sell shares without charging any fees.

But it comes with a catch.

It's called payment for order Flow, and it's illegal in most markets in the world, including the United Kingdom.

Now American politicians want to hear from this man.

Robin Hood's chief executive, Vlad tentative about why his company relies on this controversial practice.

So let's take a look at how it works.

Investors place orders through Robin Hood.

Robin Hood sells those orders to investment firms.

Those firms execute the orders on behalf of Robin Hood's investors.

Remember the Gamestop saga?

Small investors rushing to buy shares in a struggling video game retailer all to inflate the price and give a black eye to some major Wall Street players betting against game stock.

One of the biggest middleman executing orders to buy game stock shares for Robin Hood's customers was Citadel Securities.

So why, you might ask yourself, Would citadel by orders?

What is it they say about knowledge?

Is power Investment firms get market data they give Robin Hood cash on?

Robin Hood is able to give individual investors free trades.

The debate over payment for order flow bus back into the spotlight when Robin Hood briefly restricted its customers from buying more Gamestop shares, angering many of its users.

How is that a free market with in any way that's not a free market that sounds like communism thes air, dirty, dirty people?

They deserve jail time.

It also led to accusations that Robin Hood put the interests of Citadel ahead of its own users, charges that both Robin Hood on Citadel deny.

But the damage is done.