Twitter began to rollout a design overhaul last week for many of its users, and it’s on the way to everyone else sometime within the next three weeks. The changes are quite possibly the most significant shift Twitter has undertaken since its launch nearly six years ago.

The changes span the Twitter platform, including its website, mobile app, TweetDeck and advertising, at least indirectly. More importantly, the changes will be a shift for key Twitter stakeholders: users, brands and Twitter, itself.

Users

The changes Twitter has taken will be most clear for users through five different tabs:

Home: The Home tab includes the stream users have always known, but users will also be able to see trends, recommended people to follow, their direct messages and so on. The Home tab’s appearance will be consistent across computers and mobile devices.

Connect: The Connect tab is one place where users can see all the activities with them and how others interact with their content. Users can view “Interactions,” which include retweets, new followers, who favorited a tweet and who added a user to a list. “Mentions” allow individuals to see tweets mentioning them.

Discover: “Whatever you’re curious about, Discover will help you find out more.” Discover is all about serendipity. This section contains stories and trends based on who you’re connected to, what language you speak and where you’re located. Serendipity is custom to you.

Users can view everything their connections content and activity, such as their lists, what tweets they’ve favorited, what they’ve retweeted and what they reply to most. This section also provides recommendations of who to follow based on your behavior to make your experience richer. Users can also search for accounts across categories like Entertainment, Sports or Funny.

Me (user profile): The profile is a user’s presence on Twitter. This is where others can view one’s lists, favorite tweets, followers and shared content. For the user, this is where he or she will manage his or her direct messages, post a photo of him or herself, add a bio, share a location and showcase a website.

Tweet: The tweet button is certainly nothing new, but it now sports a quill look instead of the pen look from before. Users can upload photos, link to videos or websites and add location to their tweets.

The Experience: The new Twitter experience for users is all about the individual. Everything is personal based on one’s individual likes and interests. The addition of the Discover tab makes Twitter’s utility far more apparent to new users of Twitter because it shows users why they might care to use Twitter.

Brands

Twitter has taken the leads of Facebook and Google+ by launching brand-specific pages for marketers. Previously, brands and users used the same Twitter profile layout. Brand pages are only available for a handful of brands at the moment, including: @AmericanExpress, @BestBuy, @bing,@chevrolet, @CocaCola, @Dell, @DisneyPixar, @generalelectric, @Heineken, @HP, @intel, @JetBlue, @Kia,@McDonalds, @nikebasketball, @NYSE_Euronext, @GhostProtocol, @pepsi, @Staples, @subwayfreshbuzz and @VerizonWireless.

The brand pages offer some key differentiators that should cause brands that dismissed Twitter to give it another look.

Customizable Header Image: Brands can now customize the header image of their Twitter page to feature branded content, such as a logo and tagline. Previously, brands had to primarily rely on a branded background on a profile to showcase much of this content, and it was hidden behind the stream of tweets.

Featured Tweets: Promoted Tweets offered paying brands a way to feature a tweet at the top of a user’s stream, but that was the only way for a brand to guarantee the shelf life of a tweet. Other than that, tweets were buried by more recent tweets over time.

With featured tweets, brands can highlight a tweet at the top of their brand pages to highlight a campaign or promotion. These tweets can also auto-expand to show photos and vidoes from sites like Flickr and YouTube without requiring a user to take an action, which provides another easily implemented tactic for brands to cross promote various social media channels.

Tweets Separate from @Replies: A brand’s Twitter stream is now separated into tweets from the brand and a brand’s tweets to users. This allows brands to better manage customer service issues and address customer inquiries. Brands that did the best job at responding to consumers were typically punished by having streams filled with apologies and @replies with Twitter’s previous design. Now, that content is separate.

One other feature, separate from brand pages, is the ability to embed tweets on a website, blog or other platform. Users can then @reply, retweet or favorite a tweet without going to Twitter. This makes these embeddable tweets interactive experiences across the web, not just Twitter.

The Experience: The changes are certainly biggest for brands than any other stakeholder as they are now able to create a deeper brand experience on Twitter and better follow their own brand style guides, while also delivering content in the most beneficial manner through planning what tweets to feature and what content to auto-expand.

Twitter

Twitter’s moves are smart.

They’ve made it much more of a destination for users by better delivering relevant content to users and making Twitter’s best features more apparent to new users, which Twitter certainly hopes will increase its user base and make it more of a destination.

Other than users, Twitter has made some smart moves for brands. They’ve made the platform more attractive and easier to leverage, while giving brands just enough to make them want more, which Twitter hopes they’ll fulfill by looking at Twitter’s paid offerings like Promoted Tweets, Accounts and Trends. This is what Facebook has done with Pages. They’ve given brands enough candy to invest in paid Facebook ads, certainly a model that’s proven itself to work.