A quick glossary of the words, phrases, people and places involved:
Anti-protest laws: Measures Viktor Yanukovych passed Jan. 16 designed to limit protests. Dubbed the "Dictatorship Laws" by protesters, they led to a new level of violence in the Euromaidan protests and were repealed by parliament two weeks later.
Berkut: Descended from an elite force in Soviet times, the Berkut were Ukrainian riot police who operated under the Interior Ministry. At the center of much of the violence with Euromaidan protesters, they were disbanded on February 26. There have been reports that Russia is giving out passports to ex-Berkut officers.
Black Sea Fleet: A Russian naval unit based in the Ukrainian city of Sevastopol in Crimea. It’s not a particularly powerful force. It consists of an aging guided-missile cruiser, the Moskva; a large, dated anti-submarine warfare cruiser; a destroyer; two frigates; landing ships; and a diesel-powered attack submarine. Viktor Yanukovych and then-Russian President Dmitry Medvedev reached a deal to extend the lease on facilities in Crimea until 2042 in exchange for a discounted deal for natural gas.
The Budapest Memorandum: An agreement in 1994 that saw Russia, the United States and Great Britain agree to recognize the "independence and sovereignty" of Ukraine in exchange for it giving up its stockpile of nuclear weapons. Russian President Vladimir Putin suggests now that this agreement is void, as Ukraine is no longer the same state it was in 1994.
Crimea: A peninsula jutting into the northern tip of the Black Sea. This strategically-located region has been fought over many times over the course of its complicated history. Long a part of Russia, it was given to Ukraine in 1954 and, despite an ethnic Russian majority, a post-Soviet independence movement and a good dose of autonomy, it is still technically Ukrainian. However, for the past few days, what some say are Russian soldiers (and others say are armed militia) have been on the peninsula, surrounding Ukrainian military bases. They, and some of Crimea's residents, say the region rejects the post-Maidan government and wants to become part of Russia.
Crimean War: A three-year war that started in 1853 and ended up with Russia keeping Crimea even though it lost the war. Russia fought an alliance of the Ottoman Empire, France, Britain and Sardinia over disputes involving the Middle East and religion. It's widely considered the beginning of modern warfare.
Crimean Tatars: A Sunni Muslim, Turkic ethnic group that has been in Crimea since before it became part of Russia. Notably, the entire population was deported to Central Asia as punishment for collaboration with German forces during World War II. Since 1991, they have been coming back in droves: By Ukraine's last census in 2001, they were said to make up 12 percent of the population. As you might imagine, they are said to be anti-Russian and largely supportive of the Euromaidan protests. NB: It's Tatar, not Tartar.
The demographic split: To put this very simply, thanks to a complicated history, Ukraine can broadly be split between a Ukrainian-speaking West that opposed Viktor Yanukovych, and a Russian-speaking East that supported him. Some have argued that this is an oversimplification (most things are), but it does still seem to hold weight.
Euromaidan: The name given to the anti-government protests that began on Nov. 21, 2013, and eventually led to the ousting of Viktor Yanukovych. The name comes from the hopes of further European integration many had, and the name of their central Kiev location, Maidan Nezalezhnosti.
"Fascists": Both Russia's foreign ministry and Viktor Yanukovych have linked "fascist" elements to the Euromaidan protests. There is some truth to this – far-right Ukrainian nationalist groups, such as Svoboda or Pravy Sektor, have been a part of the protests. Maidan supporters, however, dispute the idea that the protests are at all dominated by these groups, and critics have accused the Kremlin of playing "political football" with (the very real threat) of antisemitism in Ukraine.
Kiev: Ukraine’s capital (also written as Kyiv) and the site of the center of protests against the Yanukovych government. Its population tends to lean more to the west and Europe than east to Russia. It was also the focal point of protests in the Orange Revolution in 2004.
Klitschko, Vitali: A former professional boxer and heavyweight champion, Kitschko was perhaps one of the most prominent political leaders at the Euromaidan protests, and certainly one of the best-known internationally. In a leaked phone call, however, U.S. officials spoke disapprovingly of his chances for leadership. He is currently leader of the Ukrainian Democratic Alliance for Reform.
Lustration: As Will Englund wrote for The Post recently, Maidan protesters have been using the phrase "lustration" to describe what they want from the new government. The term was first used after the fall of the Soviet Union to describe the purge of Communist officials from the government and bureaucracy in post-Soviet states. In Ukraine, however, it's being used to describe the purging of the government of those associated with Viktor Yanukovych.
Lviv: A culturally important city in Ukraine's west. Lviv apparently played a big role in the Euromaidan protests: It was reported to be sending 1,000 protesters a day to Maidan Nezalezhnosti at the height of the protests.
Magnitsky Act: A U.S. human rights law that created a blacklist of Russian officials last year. Bill Browder, a fund manager at the center of campaigning for the act, has told The Washington Post it should be expanded in light of the Crimea crisis.
NATO's Article 4: Poland has requested meetings under Article 4 of the North Atlantic Treaty. Here's the full text of that article: "The Parties will consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the Parties is threatened." NATO meetings for Article 4 are exceptionally rare: Only Turkey has used them before, twice during the Iraq war and once during the Syrian conflict.
Orange Revolution: The Orange Revolution was a series of protests that began in November 2004 following the disputed election of Viktor Yanukovych as president, and ended in January 2005 when his rival Viktor Yushchenko was inaugurated after a re-vote. Much like the Euromaidan protests, the center of the action was Maidan Nezalezhnosti.
Putin, Vladimir: A former KGB agent in East Germany, St. Petersburg native Putin had an unexpected rise through Russia's political elite during the 1990s before becoming prime minister in 1999, and president in 2000. Apart from a brief period between 2008 and 2012 when he was prime minister again (during which many suspected he was still the real power), Putin has been leading the country ever since. He believes that the new Euromaidan-linked Ukraine government is illegitimate and led by "fascists."
Rostov-on-Don: This is the Russian port where Viktor Yanukovych gave his news conference last week. According to Paul Sonne of the Wall Street Journal, it is the only Russian city outside of Moscow and St. Petersburg that has a Starbucks.
Russo-Georgian war: A short war in 2008 between Russia and former Soviet republic Georgia over the separatist states of South Ossetia and Abkhazia. It took just five days for Russia to overwhelm Georgia's far smaller army. Some believe that the war was a blatant act of aggression by Russia, and that it set a worrying precedent for the situation happening now in Crimea.
Sanctions: The United States and the European Union are said to be considering economic and diplomatic sanctions on Russia for its aggressive action in Crimea. For more on how that might work, read this informative post on the Monkey Cage blog by Kimberly Marten.
Sevastopol: Ukraine’s second-largest port city, located on the Black Sea in Crimea. The deep-water port is home to Russia’s Black Sea Fleet as well as the headquarters of Ukraine’s navy. Sevastopol was under siege for 11 months during the Crimean War and was heavily bombed by the Germans during World War II. It’s also a popular seaside resort and looks, feels and sounds like a little corner of Russia.
Turchynov, Oleksandr: Current acting president of Ukraine and speaker of the Verkhovna Rada. According to the BBC, he has said he would seek to reopen negotiations with the European Union, but has also said he is "open to dialogue with Russia." Considered an ally of Yulia Tymoshenko.
Tymoshenko, Yulia: Tymoshenko rose to power as one of the predominant leaders of 2004's Orange Revolution and became prime minister of Ukraine in 2005. Her eventual fallout with Viktor Yushchenko lead to her star falling, however, and she lost the 2010 presidential election to Viktor Yanukovych. In her time in office, however, she helped negotiate a new gas deal with Russia that bypassed companies linked with Yanukovych but saw Ukraine pay a higher price. After Yanukovych came to power, she was charged with misuse of power and sent to jail, only to be released in February after Euromaidan.
Ukraine: A country about the size of Texas with a population of about 46 million bordered by Moldova, Romania, Hungary, Slovakia, Poland, Belarus and — this one is important — Russia. It is considered to be the historic candle of the Russian nation and has never formed a state entity till the Soviets created it in the framework of the USSR. It got its independence when the Soviet Union collapsed in 1991. Please note, it's not "the Ukraine," just "Ukraine."
Verkhovna Rada: Often just called the Rada, this is Ukraine's parliament. It's played an important role in Ukraine's crisis, pulling back Viktor Yanukovych's more drastic anti-protest laws, releasing Yulia Tymoshenko and ultimately ousting Yanukovych.
Yanukovych, Viktor: Yanukovych was president of Ukraine from 2010 till February 2014, though he claims he is still president. Raised in eastern Ukraine, he is said to have had a rocky start in life, and ended up in jail twice (though the BBC notes that his official biography claims that the convictions were eventually overturned). He worked his way up through the post-Soviet political world to eventually run in the 2004 presidential elections but never actually took office after the Orange Revolution questioned the legitimacy of the vote and he lost the re-vote. Yanukovych's critics say he has enriched himself at his country's expense and see his lavish mansion near Kiev as evidence of that.
Yatsenyuk, Arseniy: Current prime minister of Ukraine and leader of Yulia Tymoshenko's Fatherland party. In a leaked phone call between Assistant Secretary of State for European and Eurasian Affairs Victoria Nuland and U.S. Ambassador to Ukraine Geoffrey Pyatt, Nuland and Pyatt agreed that Yatsenyuk had good economic experience.