Hi, my name is…
In the physical world (or in meatspace) we have one body, one face, one passport (assuming single citizenship), one driving license and one birth certificate. We may make copies of the latter but they are copies of a particular unique document.
In the digital world, we can have multiple email addresses and multiple Facebook, Twitter, Reddit accounts. There may be restrictions to prevent you amassing too many accounts (e.g. new Facebook accounts require a unique email address) but that just provides friction, it doesn’t outlaw them or make them impossible. With Bitcoin, Ethereum etc you are able to generate as many addresses as you wish for zero cost. Human readable identities on blockchains (like Blockstack Inc’s Blockchain IDs) need to be registered which requires a transaction fee to the blockchain’s miners. This makes the process similar to registering a website domain name that is generally purchased and registered for a fee.
If you build a web or mobile application, you need to decide how your users will identify themselves (this is especially critical for e-commerce or social media apps) where users need to identify and interact with other users.
You also have to think how your users are going to find other people signed up to the application and communicate with them reliably. Your users don’t want to spend a long time searching for their friends or accidentally send a message intended for their current boyfriend/girlfriend to their ex.
On Facebook (and LinkedIn) users are identified by their physical world identity. The upside to this is that you can search for a friend’s name directly. The downside is that if you are searching for a common name (e.g. John Smith) there will be thousands with the same name.
Twitter, on the other hand, assigns unique handles. This reduces the search time considerably if you know your friend’s handle. However, it does require you to know the handle. If the handle is something like johnsmith83762, you will need to ask your friend what his/her Twitter handle is. If you were early to the Twitter platform and registered the God handle, you’d need to upset Twitter, be hacked or be subject to divine intervention to lose it.

With decentralized applications like OpenBazaar, the former of those threats goes away. OpenBazaar core developers (or Blockstack core developers) are unable to seize your identity once you have registered it. This allows for perhaps the first implementation of an online identity that is owned by you, the user rather than being leased from a corporation like Facebook or Twitter.

Of course, you don’t need a human identity registered on a blockchain to receive and send cryptocurrencies like Bitcoin. A Bitcoin address suffices but it is not particularly human readable. An example address looks like this:
1EVp8jNWt2kTjWtLNABqPWKRhaEDvn89i8There are other companies such as 21 (and Netki) that offer its users a centralized, unique, human readable identity like Twitter but for cryptocurrencies. This means that just like the early days of Twitter, there is currently a race to register 21 profile names in case they become a primary online identity for sending, receiving and earning cryptocurrency.

Keybase is another company that provide its users with a centralized online identity. It has focused on facilitating the encrypting and digitally signing of messages but they are now branching into cryptocurrencies. You can link a Bitcoin address and a Zcash address to your Keybase identity.

Identity is one of the key tenets of both our online and offline lives. How will you introduce yourself to blockchains and cryptocurrencies?
