If you're not from the United States of America, please bear with me a moment. On this day, most Americans don't feel right if they have nothing to say about why the 4th of July matters so much to us.
People are going to be writing variations on the theme "I'm so glad I have freedom" today, and that's a worthy thing to write about, but I don't want to be another guy writing the same thing. So I'm going to get pedantic and boring for a moment. Not every American remembers now that our nation was not established on July 4th, 1776. It's easy to forget. July 4th is actually the official day given for the publication of the Declaration of Independence, a document that sought to tell the rest of the world why we were about to fight a war against our legal government, overthrowing both King and Parliament. Not someone else's King and Parliament, not some invader--our legal and rightful sovereign, King George III and the Parliament of Britain. We forget rather easily now that these people we blithely call "Americans" were Americans the way the Welsh were Welsh. They were British subjects, and they called themselves British subjects. They did not propose to repel a foreign invader, but to destroy and repel the army of their own King--the man many of them had sworn allegiance to as soldiers of the British crown!
George Washington wasn't born a general, after all. He learned to be a soldier in the service of his King. When the Americans declared that they were independent of the British Empire, only about one third of the colonists were willing to say they approved. Revolution appeared to be impossible, but we shouldn't make the mistake of thinking loyalists and neutrals were only cowards. Many of them were appalled at the criminal intentions of their representatives and wanted no part of revolution against their King, no matter what grievances they may have been nursing against him themselves.
Those who believed that revolution was necessary were considered fools by two-thirds of their countrymen. Those who believed that King and Parliament had betrayed British principles of justice were called madmen and criminals. And if there's anything to remember about the men who signed the Declaration of Independence, it's this: these were men with everything to lose. These were men who had made great successes of themselves under the King and the Parliament. They were the cream of British society in the Americas. They had fortunes, land, families, and positions of influence. They risked all those things plus the hangman's noose by signing the Declaration. They signed it anyway because they believed that they had a chance to deliver on the promise of British justice and fairness.
The war they fought was not perfect, nor was the nation it created--nor is the Constitution that replaced that nation and created the one we have now. All they managed to do was to create a nation that allowed more freedom and power for the individual citizen than just about any nation in history. Blow stuff up, go to a picnic, sing patriotic songs with your neighbors. If today is not a day worth celebrating, I can't think of one.