I'm a newcomer to Steemit, introduced by 
What is Steemit?
Steemit is a social media platform. What sets it apart is that it is based on distributing value to those who contribute value - distribution in the form of the blockchain-based STEEM, and contributions in the form of content, whether that be pictures/videos/stories. This distribution has been designed to adhere to the "sweat equity" principle:
all forms of capital are equally valuable
In other words, contributions of time and effort are worth just as much as contributions of cash/STEEM. In return for contributions, Steemit provides:
- A hub for content aggregation - news/discussion/media.
- Cryptocurrency rewards!
Transactional Scale
Steemit's infrastructure can technically handle a larger userbase than Reddits. It is built using Graphene - Reddit in 2015, if operating on blockchain, would produce 250 transactions per second. Steemit is capable of handling up to 10,000 transactions per second without any signicant optimisations, using lessons learned from the LMAX Exchange (can handle 6 million transactions per second!)
Problems
- Valuing the worth of a contribution, and scaling that up to potentially (hopefully!) millions of people.
Instead of using micro-transactions or per-post paywalls, which are often avoided at all costs by users, users vote on content, and Steemit then calculates the relative worth of that piece. This means that votes are imperative to Steemit's ability to pay out content creators fairly and accurately. As such, votes are also incentivised - Steem rewards voters based on:
- Their contribution to the promotion of a piece of content.
- The reward paid to the creator of that content.
What are STEEM/SP/SMD?
STEEM
Steem is the fundamental currency of Steemit. It should be converted into SP/SMD to reduce the effect of dilution over time. The reason for this dilution is that steam is increasing in supply by 100% per year - holding STEEM for a day without converting it leads to an effective dilution of 0.19%. This sounds high, but in reality is insignificant - compared to STEEM's or Bitcoin's price volatility or Bitcoin's market fees for example which can be over 0.4%. Something to note - STEEM's price is calculated from it's one week median, sampled every hour. This helps factor out price fluctuations and gives the community 3 and a half days to sort out any problems if the price feed was to become corrupted, as well as removing the possibility for timing attacks.
SP
SP stands for Steem Power. Steem Power is Steemit's way of assuring value to long-term investors; which are needed for long-term plans! It can be thought of as a share in the STEEM pool, and as an "access token". These SP stakeholders are guaranteed 9 STEEM for every 1 STEEM created to pay users for contributions. SP is an access token as it is required to vote on content.
"Powering Down" - The act of converting SP to STEEM. SP can only be converted to STEEM over the course of 2 years - 104 equal weekly payments, calculated at the current rate.
"Powering UP" - The act of converting STEEM to SP. This is done instantly, at the same ratio of STEEM:SP in the STEEM "share pool", therefore not diluting current holders of SP.
SMD
Not what you think it might stand for - SMD refers to Steem Dollars - a currency worth a dollar's worth of STEEM! SMD are created and distributed by the blockchain, removing potential for abuse through conversion attacks, and can only be converted into STEEM, not vice versa. SMD are basically "short term debt instruments that can be converted into ownership in the future". Summarised, SMD are STEEM's stability mechanism.
I'd love for someone to elaborate a bit more on anything I may have missed or gotten wrong!
Steemit's Future
That all being said, where do I see Steemit heading? From what I can tell from my very short stay here, the community is mightily invested in producing content, and there is a general aura of connectedness, which is great! Reading the white paper, it's easy to tell a lot of thought has gone into creating this, and making sure it's stable, viable and has enough of an incentive to acquire a bigger userbase over the coming weeks/months/years.
I do believe that there are a fair amount of people on Steemit who are purely posting low-quality content in hopes of making money, without realising that real value only comes through a long-term investment of time/effort, but I think the ratio of these people to the true content creators will only continue to shrink, which is good for the community, and hopefully will increase the quality of discussion being had. Nothing quite like Steemit has ever been done before to my knowledge, and it looks very promising!
Thoughts?