Short answers, pulled from the story.
The first income tax is recorded in 9 CE, when Emperor Wang Mang of the Xin dynasty imposed a 10% tax on net earnings from activities such as fishing, shepherding, and trading. Evaders faced one year of hard labor and confiscation of all their property. The tax was abolished in 22 CE after generating widespread public discontent.
The modern income tax is typically dated to 1799, introduced by Prime Minister William Pitt the Younger in his budget of December 1798 to fund the French Revolutionary War. Henry Beeke suggested the idea. The graduated tax started at 2 old pence in the pound on incomes over £60 and reached a maximum of 10% on incomes above £200.
The US federal government imposed its first personal income tax on the 5th of August 1861, at a rate of 3% on incomes over $800, to help pay for the Civil War. A peacetime income tax was not passed until 1894, and a permanent federal income tax required the Sixteenth Amendment in 1913.
The Supreme Court ruled the 1894 income tax unconstitutional because the Constitution required direct taxes to be apportioned among the states by population, and the tax did not meet that requirement. The Sixteenth Amendment, ratified in 1913, resolved this obstacle and enabled a permanent federal income tax.
Bracket creep occurs when inflation raises nominal wages and salaries into higher tax brackets, increasing the proportion of income paid as tax even though real purchasing power has not grown. Most progressive tax systems are not automatically adjusted for inflation, so the effect is a gradual real tax increase unless lawmakers periodically update the brackets or rates.
Finland, Norway, and Sweden make personal income tax filings publicly available. Sweden has published this data in the annual directory Taxeringskalendern since 1905, giving the practice a history of more than a century.