Musing.io is a platform/dapp on the Steem blockchain. You can post content here just like Steemit and Busy, but in a slightly different format. If you already have an account to access the Steem blockchain (like Steemit, Dtube, Dlive, etc.) then you can use steemconnect to login and begin using musing.io.
This is how the musing.io describes itself:
“Musing is a question and answer platform, built on Steem's blockchain, that rewards you with tokens for answering peoples' questions!”
What they are doing would seem pretty similar to Quora but there is a major difference. That would be the fact that the whole thing is based on the Steem blockchain and thus the content (both questions and answers) can be rewarded. Neither Quora nor Yahoo answers have this reward system. The only incentive there was to gain a few likes or whatever they called it.
This model for a website/app may not be new, but incentivization of a platform based on a question-answer format is quite a breakthrough. The modern-day internet is purely based on making people work without paying them. Every click we make, every alphabet we type is being used directly or indirectly to profit somebody (there are plenty of people who still will argue with this and to them I politely ask that they open their eyes).
On musing if I ask a question and somebody answers it for me then I can go ahead and upvote that answer based on its quality. Similarly if somebody asks a question that we feel is relevant then we upvote that question and reward the person who asked it. I was once discussing Quora with someone here on Steemit and I am quoting myself not because that I said something great but because I am lazy ;-)
"Last year I registered at quora and answered a few questions and in return a few of them were answered for me. I'll be truthful here, quora started to feel like an expensive hobby after a few days. You waste tons of time answering questions and for your efforts you get nothing...... literally"
Musing.io makes several good points as to why incentivizing questions and answers could be a good idea. First, they mention that the quality of answers could be great if people were being rewarded for answering questions of other people. It obviously goes without saying that people would be interested in answering in the first place because they see the rewards that they might get for their answers.