Just to give you some perspective:
1. Yanukovich was elected with strong pro-Russian campaign, but still promising of bringing Ukraine closer with the EU.
2. When approaching a date for signing a previously negotiated trade association agreement with the EU, he suddenly shifted his position and turns 180 degrees, speaking of prospects about joining the Eurasian Economic Union instead - a position affected by Russia, undoubtly, as Putin promissed $15 billion economic aid with 1/3 gas price discount.
3. People get angry at the democratically elected president (who already changed the constitution to gain more power) and go to the Independance Square to hold a peaceful protest, numbering arround 2000 people (21 Nov 2013).
4. In the next few days, people organize with social networks and on the 24th of November about 100 000 people gather at the square to protest. This time as they try to "occupy" a government building, there are clashes with the police, about 400 people are injured. (Here's a random video from this day, just to give you a perspective about the type of people on these protests and the kind of atmosphere there)
5. Protests continue in lower numbers in the following week, when on the 29th as protesters learn the news that the EU Trade Association has not been signed, people gather again and they begin to ask for the resignation of the Parliament and the President.
6. Early in the morning on 30 Nov the Berkut special riot police, executing orders of the legitimately and democratically elected President of Ukraine, disperse the non-resisting protesters. Here's another video, which I think really describes this better than any words I can think of...
7. The next days, people are outraged about the actions of the President and gather in larger numbers culminating on the 8 Dec, when about half a million people hold peaceful protest on the now dubbed Euromaidan (maidan = square in ukrainian). (video)
Without going into further details the next few months, people persist with the protests, eventually turning violent and toppling the President and the Government. When a president begins shooting at people, who want just his resignation, he ceases to be a democratically elected official and turns into a dic(k)tator.
I am deeply passionate about this topic, because here in Bulgaria, we also held for months everyday, popular protests against the blatant and corrupt government, against the oligarchs and against the government propaganda. We did so peacefully - I stood in live chain holding hands with others, while police in riot gear was beating unarmed old people and women in front of me, so I can not judge too hard people like the ukrainian citizens, who respond with violence.
Because democracy, my friend, is NOT voting for a ruler, who can do whatever he wants for his term, including breaking his promisses, which elected him in first place.
It is NOT sitting passively to wait for election day, when you see corrupted officials trying to boost their power and wealth.
It IS the combination of informed society, independant media and separation of powers to act as check and balances that best implement a modern day democracy.