Basic Concepts in the Steemit Ecosystem
What is a Steem Dollar?
This is a sister currency to Steem that is pegged to the US dollar. Each SD can be used to purchase approximately 1 US dollar worth of Steem.
What is Steem Power?
This is a special form of Steem. SP is required to vote on content on the Steemit platform. The more SP you have the greater the value of your vote. In order to acquire SP you must either convert Steem to SP by a process called powering up or alternatively earn SP through posting or curation rewards. Unlike Steem, SP is not a "liquid" currency which you can transfer and spend whenever you want. In order to use it in this way it must be converted back to Steem in a gradual weekly process known as powering down. This can be initiated from your Steem wallet and happens over a period of 104 weeks.
What are Whales, Dolphins and Minnows?
These are terms that people use to describe Steemit users with different amounts of Steem/SP. There are no formal definitions. As the names suggest whales have the largest amount of SP, followed by dolphins in the middle and minnows at the bottom. Where you set the boundaries for each is entirely subjective. There is a lot of talk about whales because they have the largest voting power and influence on the platform.
Steemd uses a slightly different system which you can see here (https://steemd.com/distribution):