Live-streaming apps are the thirstiest of all media. A Facebook post wants a like, a tweet begs for favs, and a snap means little without a response. But for sheer drop-everything, look-at-me arrogance, nothing beats the push notification that says "LIVE NOW." I’m doing literally anything, the notification says. Watch now, or you’ll miss out forever.

The surprise emergence of Meerkat as a social phenomenon this year has been accompanied by a frequent complaint: the links are usually dead by the time you click them. All that thirst, and it’s totally unslaked. But even as the app began to be discovered by celebrities and other high-profile users, Twitter employees began shouting that a better solution was on the horizon: Periscope, an app the company acquired in January for a reported $100 million. Periscope, they said, was more than a way to stream yourself live: it’s also a way to play those streams back.

Replays are Periscope's killer feature

And now we can see for ourselves. Periscope arrives today on iPhone, with streams also viewable on the web. (An Android version is forthcoming.) Like Meerkat, it allows you to broadcast whatever you’re doing — whether it’s breaking news or making breakfast — live, through video, with a couple of taps. Unlike Meerkat, Periscope can save streams so that you can replay them later. It turns out to be Periscope’s killer feature — and the main reason that it’s likely to become my live-streaming platform of choice.

For everything it got right, Meerkat still looks like an app built in eight weeks — which it was. Periscope has been in development for more than a year, and the app arrives showing nice attention to detail. You sign in with Twitter, and the first thing you see is a list of streams that are currently live. Below it, you’ll see a list of recent streams. Not all can be played back — when you record yourself, you can stop your stream from being replayed with a single tap. But they save by default, and the result is an app that can actually be browsed.

Periscope is warm and fuzzy

Where Meerkat in its current incarnation is a bare-bones utility, Periscope is more warm and fuzzy. It introduces the world to the concept of infinite hearts — while you watch a stream, you tap to send the person recording it a heart. As soon as you tap, the heart appears on the screen for you and the rest of the audience to see. And you can tap as many times as you like — you can even double-tap to send two hearts simultaneously. It seems silly, but the multi-heart approach serves a purpose: they let the person recording know that their audience still appreciates what they’re doing, even several minutes into a stream.

The result is that on popular streams — like that of retired astronaut Chris Hadfield, an early user — hearts fizz furiously in the corner of the screen throughout every broadcast, rising up like soda bubbles. "It’s like the crowd going wild — who doesn’t like that?" says Kayvon Beykpour, Periscope’s co-founder. It’s all part of an approach to make broadcasting less intimidating to the average person. "We don’t want this to be a tool for very few people," he says. Like a lot of people lately, Beykpour says broadcasting is finally a tool ready to be embraced by the masses.

You won’t be able to launch Periscope directly from the Twitter app, at least not for a while. "We don’t think we need to start there," Beykpour says. "We think this deserves to be a separate experience indefinitely." Still, there’s a reason Twitter scooped up Periscope: Twitter is a mostly live experience, and so is its new broadcasting app. "We always thought that what we were building, if successful, could be a real-time visual pulse of what’s happening around the world," Beykpour says. The vision for Twitter is much the same.

The push notifications are out of control

The big problem with Periscope and its peer apps, as I see it, is that crazy thirst for engagement. Imagine getting a push notification each time every single person you follow on Twitter tweeted. That’s Periscope in a nutshell — but instead of easily digestible tweets the notifications lead to livestreams, some of which are many minutes long. The result, at least for me, was turning off push notifications for Periscope as soon as I could. And I was following fewer than 50 people! I’ll still use the app, but on my terms — and the team really ought to develop some more granular controls around notifications.

Of course, that I can browse it on my terms is only thanks to the fact that Periscope thought to make its streams available for replays. I’m not quite prepared to say the app is a Meerkat killer — Meerkat has been growing its user base at 30 percent a day, and it just announced a big new round of investment this morning. But for now at least, Periscope better matches the way that most of us actually use the internet. As of today, Meerkat has a lot of catching up to do.

Verge Video: What is the future of communication?