• Difficulty (https://en.bitcoin.it/wiki/Difficulty):
  • Difficulty is a measure of how difficult it is to find a hash below a given target. The Bitcoin network has a global block difficulty. Valid blocks must have a hash below this target. Mining pools also have a pool-specific share difficulty setting a lower limit for shares.
  • Re-targeting: recalculation of the difficulty target occurs every 2016 blocks.
    • Formula for difficulty:

      difficulty = difficulty_1_target / current_target (target is a 256 bit number)

https://en.wikipedia.org/wiki/History_of_taxation_in_the_United_States

Summary

• Colonial protest against British taxation policy in the 1760s, leading to the American Revolution
• The independent nation collected taxes on imports (“tariffs”), whiskey, and (for a while) on glass windows
• States and localities collected poll taxes on voters and property taxes on land and commercial buildings.
• State and federal inheritance taxes began after 1900, while the states (but not the federal government) began collecting sales taxes in the 1930s.
• The United States imposed income taxes briefly during the Civil War and the 1890s. In 1913, the 16th Amendment was ratified, permanently legalising an income tax
• Taxes were low at the local, colonial and imperial levels throughout the colonial era.^[1] The issue that led to the Revolution was whether parliament had the right to impose taxes on the Americans when they were not represented in parliament –> “No Taxation without Representation“
• Americans rose up in strong protest –>Boycotts forced Britain to repeal the stamp tax, while convincing many British leaders it was essential to tax the colonists on something in order to demonstrate the sovereignty of Parliament.
• Townshend Revenue Act: They placed a tax on common products imported into the American Colonies, such as lead, paper, paint, glass, and tea. In contrast to the Stamp Act of 1765, the laws were not a direct tax that people paid daily, but a tax on imports that was collected from the ship’s captain when he unloaded the cargo.
• The Tea Act of 1773 received the royal assent on May 10, 1773. This act was a “drawback on duties and tariffs” on tea. The act was designed to undercut tea smugglers to the benefit of the East India Company.
• The Boston Tea Party was an act of protest by the American colonists against Great Britain for the Tea Act in which they dumped many chests of tea into Boston Harbor. The cuts to taxation on tea undermined American smugglers, who destroyed the tea in retaliation for its exemption from taxes. Britain reacted harshly, and the conflict escalated to war in 1775.

A collection of useful links: