Choosing Sides
To understand Northern Ireland, you first must understand who is involved in the sectarian game, because the battle between Republicans (those who believe the North should become part of the Republic of Ireland; also called "the Catholics," depending on who's talking), and the loyalists (those who are loyal to the British crown, and think the North should stay, as it is now, part of the United Kingdom; also called Unionists or "the Protestants") defines this region to this day. The problem is that both sides have splintered over the last decade, and so it's hard to keep up with who's who.
The Republicans are now divided among devotees of the IRA (the Irish Republican Army), the "Real" IRA (a rebellious faction formerly part of the IRA), and Sinn Fein (also splintered from the IRA, and now its political face). Supporters for this side have the green, white, and orange Irish flag hanging from their homes and businesses.
The loyalists are divided among a variety of paramilitary groups including the UDA (Ulster Defence Association), the UDF (Ulster Defence Force), and the UVF (Ulster Volunteer Force). Much of the violence in the last decade has been the result of turf wars between those Protestant groups. Supporters of that side have the British Union Jack flag flying from their homes and businesses.
These days, most, if not all, of these groups are more involved in organized crime than political struggle, and all of them have been lumped together by pundits under the new term "Irish mafia." Massive bank robberies (all of Northern Ireland's currency was withdrawn and reissued within 1 week in 2005 after a gang suspected to be connected with the IRA stole £22 million/$39 million in a bank heist), importation and sales of illegal weaponry, and drugs are all blamed on the same factions that once battled for political power here. Most Irish people will tell you that they're sick of the lot of them -- however don't ask unless you know the person you're talking to. It's an extremely sensitive subject that should not be brought up casually. If curiosity is killing the cat, take one of the Black Cab tours and you can ask your driver questions to your heart's content.