It's far less important than it used to be, because so many social media businesses are much more reliant on their apps than their desktop websites these days.

Instagram launched (and grew fast) with the domain instagr.am, for instance.

It is very important for branding and authority. But it is more important for you to have it than your competitors.

If you can get it, then get it. If you can't, then your app or service or offering will need to be amazing to overcome branding, authority and trust issues.

The reason the giants have the .com is because it is necessary to demonstrate authority, longevity and trust.

Good dot com names are also indicative of good business sense. Planning, creative inclination and or the ability to buy a good domain $2000 to $10000 or more say a lot about your business.

This topic arises for me daily, and I've written numerous articles dealing with it in whole or in part. You'll get a lot of "I reckon" answers from people whose main professional focus is elsewhere, but I doubt they've been immersed in the question as I have been for years – researching actual domain market trends, analyzing brands' behavior online, and advising clients on domain selection.

Every week, I observe companies who've already achieved some measure of success with a website built on a different TLD nevertheless pay a substantial amount of money to obtain the matching .COM. In fact, I'm publishing an article about some of last week's upgrades tomorrow at DomainNameWire.com, just as I did the previous Thursday.

These companies buy the .COM belatedly, for pressing reasons of their own, without any cajoling from me. They pay a lot to do it. So it MUST matter. If it didn't, they wouldn't.

Where is Del.icio.us today? Delicious.com. And Join.me (which I'd consider a great non-.com name) still bought JoinMe.com even after paying $45,000 for their .ME.

I'm not a .COM purist. Half of my own domain portfolio is composed of other TLDs, ranging from .ORG and .NET to .FM, .TV, and .CLUB – to say nothing of country codes.

.COM isn't always the only answer. But for global or U.S.-based projects, a business must seriously evaluate any decision to neglect .COM.

Some of the issues include brand protection, search-engine competition, ambiguity for customers in SERPs, perceived amateurishness versus professionalism, traffic leakage, email misdirection, susceptibility to phishing, familiarity, memorability, and permanence.

Constantly having to differentiate your domain from a similar domain that you don't own gets old very quickly. And sending
customers to Google to run the gauntlet of ads from your competitors is never a prudent alternative to direct navigation.

Consumers (especially in the USA) expect .COM. It's the default. We can talk about Facebook and Google and Instagram purely in terms of their brand name primarily because the suffix is assumed. When the TLD isn't obvious, it must be spoken. That can sometimes be quite cumbersome and tends to lead to confusion or misremembrance.

As a namer, I generally like .COM because it is a blank canvas. It gives a startup the widest range of branding options. Building on, say, .CLOTHING or even .CLUB imposes those keywords as limits on brand identity.

There have been trends in .LY and .IO. But I don't see much staying power in the former (which has resulted in many expensive .COM rebrands). And .IO has little mass consumer appeal. It's mainly fashionable within the bubble of tech startups.

I plan to launch projects in a range of TLDs myself – not just .COM. Personally, I'm TLD-agnostic. I can cite examples of brands that did just fine without .COM. And I usually recommend some outlandish non-.COM name ideas to clients alongside .COMs.

There is no one-size-fits-all answer. I hate giving general advice. If you have a particular project and a particular set of brand name / domain options, then let's look at the particular case.

I upvoted Caroline's answer because it's the most direct answer to your question. Joseph's perspective is that of a domain-owner and although thoughtful and nuanced for a very general question, I vehemently disagree with the assertion that "consumers expect .COM in America." I think that might be true for eCommerce, but there's plenty of other ways to build trust than just the domain itself.

Oscar's passionate assertion of the value of the .COM is just not something I would give credence to. It's absolutely a nice to have and if your business scales, not owning it early will only drive up the price later. That said, I'd rather validate the core offering first, and then invest in buying the .COM before massive traction but ahead of a lot of traffic and publicity.

I generally start with .co as the preferred domain when the .COM isn't available.

I'd say it even depends on your target audience. For example, .io domains are quite popular in tech. Other domains never really took off like .mobi for example. If you can spell a word or the name of your company with the domain extension that also becomes a clever trick that can work.

Clarity.fm is an interesting one in itself. Of course it's fine right? We're all here and found it. Though fm would be for radio, right? It's actually for the Federated States of Micronesia. Though it's commonly considered "radio." Clarity is not a radio station so it's an interesting choice, but I don't think it was a problem for anyone.

So it's not as big a deal as it used to be. Though it's certainly still valuable and coveted. It can sometimes be used for authority as well. If you don't buy up all the TLDs sometimes people will buy the .net version etc. They do this in hopes to get people from search engines (or mistakes) over to see ads. The .com gives you authority in that regard. Well, aside from the blatant ads on the other site =)