The Declaration of Independence was officially adopted on July 4, 1776, and is known to be an important document in claiming freedom from Great Britain and for the United States to become independent.
The relationship between the colonies and Great Britain was worsening over the years, as Great Britain had stopped leaving the colonies alone, which angered many of the colonists. Things like "taxation without representation" occurred, which is where Great Britain was putting taxes on goods without any representation or say from the colonists. A lot more happened between them though, which caused their relationship to be rough.
The Declaration of Independence places considerable blame on the British Parliament, but mostly King George III. While they did blame the King because he did a lot of bad things to them, they felt it would be more powerful to blame the King rather than just a group of people called the British Parliament. With that being said, they did place blame on the British Parliament as well. They would mention that the British Parliament ignored their want for help and essentially turned a blind eye to what the King was doing, letting the terrible actions continue with no help.