Short answers, pulled from the story.
The Battle of Sinop on the 30th of November 1853 triggered the Crimean War when a Russian squadron destroyed an Ottoman patrol squadron in the harbor of Sinop. This naval massacre transformed a regional dispute into a full-scale war involving the British Empire, the Second French Empire, the Ottoman Empire, and the Kingdom of Sardinia-Piedmont against the Russian Empire.
The main belligerents in the Crimean War were the British Empire, the Second French Empire, the Ottoman Empire, and the Kingdom of Sardinia-Piedmont fighting against the Russian Empire. These nations joined the war after the Battle of Sinop forced Britain and France to abandon their diplomatic neutrality and enter the conflict in March 1854.
The Crimean War officially ended on the 30th of March 1856 with the signing of the Treaty of Paris. This treaty forbade Russia from basing warships in the Black Sea and granted Christians in the Ottoman Empire a degree of official equality.
The Crimean War was one of the first conflicts to use modern technologies such as explosive naval shells, railways, and telegraphs on the battlefield. It also marked the first use of ironclad ships in naval warfare during the attack on Kinburn in the Dnieper estuary in September 1855.
The Crimean War weakened the Russian Empire by defeating the Imperial Russian Army, draining the treasury, and undermining its influence in Europe. The defeat forced Russia's educated elites to identify fundamental problems and became a catalyst for reforms including the emancipation reform of 1861 which abolished serfdom.