Short answers, pulled from the story.
The three official Confederate national flags were the Stars and Bars (1861-1863), the Stainless Banner (1863-1865), and the Blood-Stained Banner (1865). Each successive flag was adopted in part because of criticisms of its predecessor, particularly the Stars and Bars being too similar to the Union flag.
William Porcher Miles, a Democratic representative and chairman of the Confederate Congress's Committee on the Flag and Seal, designed the Confederate battle flag. The design was inspired by a flag flown at the South Carolina secession convention in December 1860, and Miles revised it after feedback from Charles Moise, who asked that religious symbolism be removed, leading Miles to replace the upright cross with a diagonal saltire.
The Stars and Bars was replaced because it looked too similar to the Union's Stars and Stripes, causing dangerous battlefield confusion at the First Battle of Manassas. Confederate soldiers also objected to it on ideological grounds, with one newspaper editor calling it "universally hated" and George William Bagby writing in January 1862 that "everybody wants a new Confederate flag."
The Stainless Banner was criticized for being too white and for resembling a flag of truce. Military officers warned it could send a dangerously mixed message, especially aboard naval vessels where the large white field became easily soiled. Some Confederate soldiers cut away the white portion of the flag, leaving only the battle flag canton.
Generals Beauregard and Johnston and Quartermaster-General Cabell approved the Confederate Battle Flag's design at the Ratcliffe home near Fairfax Court House in September 1861. President Jefferson Davis arrived by train at Fairfax Station shortly after and was shown the design. The flag was formally distributed to Confederate soldiers on the 28th of November 1861, in ceremonies at Centreville and Manassas, Virginia.
A YouGov poll of more than 34,000 Americans in 2020 found that 41% viewed the Confederate battle flag as representing racism and 34% viewed it as symbolizing Southern heritage. A Politico-Morning Consult poll of 1,996 registered voters in July 2021 found 47% saw it as a symbol of Southern pride and 36% as a symbol of racism.