When Google showed this a piece of cardboard at its conference, everyone freaked out

While Google hosts its annual developer conference on Thursday, Twitter is afire with excitement about...a new piece of cardboard?

Okay, okay - it's a virtual reality headset, powered by your smartphone, and Google's updating the headset to accommodate phones up to six inches large. The system is called "Google Cardboard" (fittingly), and it's been Google's main point of entry for virtual reality since last year's developer conference.

As The New York Times' Farhad Manjoo puts it:

Complimentary Tech Event

Transform talent with learning that works

Capability development is critical for businesses who want to push the envelope of innovation.Discover how business leaders are strategizing around building talent capabilities and empowering employee transformation.Know More

Smart! Naturally, the inexpensive and open approach that Google's taking to VR is spurring the Apple critics to take up arms.

Alongside the new headset, Google announced a variety of virtual reality initiatives. First up is a virtual tourism application aimed at schools. It's named "Expeditions," and it's a fully integrated system for teachers and students to travel together around the world, under the oceans and into space - all in VR, of course. The system comes in a cardboard box, as Google demonstrated in this intro video:

While students use the headset to, say, explore the Great Wall of China, the teacher - using a tablet - is able to guide the experience.

People are also freaking out about Expeditions:

And they should be! Expeditions intends to enable inexpensive field trips to children all over the world.

Even better, Google's creating a VR-ready version of YouTube for use with its Cardboard headset, and working to create 360-degree video with its "Jump" initiative - a hardware and software set that makes it easy to film and produce 360-degree videos.

The initiative is already supported by the world's leading action camera company, GoPro, and will be supported by the upcoming 360-degree camera that GoPro announced earlier this week.