You've heard of Christmas in July. But Black Friday?

That's what some are calling Amazon Prime Day - which starts tonight and runs all day tomorrow.
Amazon is poised to bring in a Billion dollars for the 30 hour event which is running during the traditionally slow summer season. This is yet another way the online retail giant is changing the way we spend..

The old "Black Friday" shopping-mall frenzy may be facing competition from a summertime counterpart... Happening all online...

This is the third Amazon Prime day, starting tonight at 9 p.m. And this year it's expanding from 24 hours to 30, promoting deals on tens of thousands of items...from televisions to toasters.

“Prime day is really just a giant marketing day for Amazon. They're going to sell a ton of products and they're also going to get a ton of new prime subscribers, says Business Insider Lauren Lyons Cole.

Amazon doesn't give specific sales figures... But last year the company said it sold two million toys, one million pairs of shoes... 215 thousand pressure cookers... And 90 thousand TV's. All in one day.

“Prime day gives you a good opportunity to buy that special purchase for yourself and save money on it at the same time,” says Lyons Cole.

This year, experts say look for big discounts - up to 25 % off smart TV’s, 30% on some apparel like Under Armour, and even up to 50% of certain video games and consoles.

The catch? You have to be a Prime member to get those deals -- and that costs $99 a year. But you can sign up for a 30 day free trial.

In the meantime... Amazon's competitors are rolling out deals of their own.

Target has already kicked off it's back to school sales... Offering deals on school supplies and clothes. And if you have a Target "red card" you get free shipping on most orders.

As for Walmart - they say they offer great deals every day. And they point out they also offer free two-day shipping.... With no membership fee.

But when it comes to creating its own "shopping holiday" buzz in July... Amazon is primed-and ready.

If you're thinking about checking out Prime day, here are two tips:

  • Resist the urge to just click and buy.
  • Do some comparison shopping on sites like Walmart and target to make sure you're really getting the best price.