Since Axiem asked, and others might be wondering, I thought I'd give a brief explanation of this 'election' thing that we're having shortly - how it works, who's running, etc.
Despite the name, the 'general election' isn't. It's actually 650 independent elections in diferent geographically-defined areas (533 in England, 59 in Scotland, 40 in Wales, and 18 in Northern Ireland). These areas are called "constituencies", but in other countries would be "seats" or "districts". And even here, they're talked about collectively as "seats" - we talk about someone standing in a constituency, the swing in a constituency, etc, but about the government gaining or losing seats. I'll just say 'seats' throughout, since 'constituency' is frankly a bugger to type. These seats attempt to be of roughly equal size, but that doesn't always work - the Isle of Wight has a huge seat because they prefer to have one MP for the island rather than two MPs they have to share with someone else. At the other extreme, some Scottish areas are overrepresented because they're already so huge that if you made them bigger it would just get silly. Seat boundaries are set by a largely independent commission.
Each constituency elects an 'MP', a Member of Parliament. They do so in a very simple way: everyone votes for who they want to be the MP, and the one with the most votes wins.
Think of this as basically like voting for the US House of Representatives.
Who selects the MP candidates?
That's a matter for the parties. In general, traditionally, there was a 'local association' for each party in each seat, and they picked their favourite candidate. This is still theoretically the case, but over time the central national parties have exerted more and more power over the selection process, so now it's mostly up to the central party. If an MP keeps voting against their party, their party will "withdraw the whip" and forbid them from being selected for that party again. Occasionally they stand as independents and win... but it's very rare. So MPs are terrified of their parties and do whatever they're told.
MPs sit in the House of Commons, the equivalent of the House of Representatives. The big difference is that there is no separate vote for 'President'. 'Originally', our equivalent of the President was... well, the King, but other than him, it was the Speaker of the House of Commons - so imagine America without a Senate or a President, with Paul Ryan in charge. Now, the Speaker has become an almost entirely apolitical figure - they're elected from among the MPs, so they begin with a party, but they're meant to act apolitically (eg traditionally they don't vote and everyone agrees not to challenge them in elections).
Instead, our ruler is the Prime Minister. The position has existed informally for centuries, but only began to be legally acknowledged in the early 20th century, and it's still debateable about whether it's constitutionally recognised at all. The PM is simply "whoever can command the House" - whoever can get shit done. They're not formally voted on - the Queen asks someone to 'form a government' and they either can or they can't. In practice, however, the PM is almost always the leader of the largest party in the commons. They serve at the pleasure of their party - they are appointed and dismissed through internal party processes. So, Margaret Thatcher won many elections, but was suddenly deposed by her own party.
So, in each seat, the one with the most votes wins. In the Commons, the one with the most seats wins. Sometimes, nobody gets more than 50% of the seats, and we have a "hung parliament" - these are extremely rare, and generally mean another election soon after. [In these cases, either the largest party can form a 'minority government' and hope that their rivals won't all gang up against them; or, two or more parties can join a formal 'coalition'. But, as I say, both options are incredibly rare.]
But what about the Lords? And the Queen?
The House of Lords is the upper house. It is not formed of hereditary peers anymore. Instead, they are 'life peers' appointed by the parties in rough proportion to their strength in the Commons. More peers get appointed every year and they serve for life (if they can be bothered), so the number grows and grows. Life peers include retired politicians, "people who have contributed greatly to the nation" (i.e. rich businessmen who have given lots of money to a party), and some lawyers and academics. There's also a small number who, as a concession to the old aristocracy, are elected by and from among the aristocracy to represent them.
The important thing about the Lords is that they can't do much. Their job is 'scrutiny', and they're basically a brake: bills go through the Commons in a rush, and the Lords can slow them down, debate them, point out problems, and, in very rare cases, delay them for up to a year.
The Queen then signs them. The Queen has important theoretical, constitutional functions. She tells PMs when they have to admit that they've lost, for instance. She can theoretically refuse to sign a bill that abolishes democracy. And when push comes to shove, the army would feel very unhappy if they were given an order that the Queen didn't approve of, like shooting people in the streets. She also meets with the PM every week, and basically acts as "the only person who really doesn't care what the PM thinks about her", so can give advice and warnings that others can't. But in terms of actual, practical political power... she has none. She is, as it were, an emergency safety valve.
So who are the parties?
You're following so far? There's an election in every seat, and the party who win the most seats get to be in power. We're not talking puny US power with checks and balances, either. Yes, there are parliamentary committees, and they're robust places for criticism, but they have no real power. The PM has the power. The PM decides what bills to put to a vote, and if she's the PM then by definition she has a majority of the votes, so she always wins. Years go by between PM defeats. They basically only happen when the PM only has a razor-thin majority, or on really emotive issues. [these are called 'matters of conscience', and if the PM thinks they will lose a vote, then they make it a matter of conscience, which means that people don't have to obey their parties, so it's not embarrasing when they don't].
Traditionally, since the early 20th century, there have been two serious parties:
The Conservatives, a.k.a. The Tories. The Conservatives emerged from schisms within the Tory Party in the 19th century, and have kept the old name as a nickname. The Tories are traditionally right-wing. They cover everyone from "One Nation" Tories, who believe in the rich caring for the poor, through to free-market libertarians, who... don't. They're also traditionally the party of the religious and the moral and the old and the white and the rich. They are usually in power.
Labour. Labour came out of the trade union movement, and the unions remain important to it. Labour are theoretically left-wing. They are the traditional party of the working class, and a few do-gooding middle class folk in certain areas. They are also traditionally more welcoming to non-white voters, and to voters in marginalised areas of the UK - traditional strongholds include Wales, Scotland, and the North, and particularly in urban areas.
Alongside these there has been a third party, variously known as The Liberals, The Alliance, and The Liberal Democrats (currently). Or 'lib dems'. They were in power a lot in the 19th century, having emerged from the Whigs, but collapsed in the early 20th century. They come and go, sometimes having dozens of MPs, and sometimes having 'few enough that they can hold their party conference in the back of a taxi'. ('party conference' = 'convention').
In modern times, however, the party system has fallen into chaos. Alongside the above three, there are also:
The SNP. The Scottish National Party. They want more power for Scotland - ideally independence - and a generally left-wing platform of policies. The voting system overrepresents them in parliament.
Plaid Cymru. The Welsh version of the SNP, but less succesful.
UKIP. The UK Independence Party. They want Brexit, and a generally far-right platform of policies. Their leadership is traditionally a bunch of weirdo rich guys who appeal to upper-class english stereotypes and wear tweed a lot. But their voters are usually poor and uneducated working-class people.
The Greens. They believe in... stuff. Bicycles. Beards. Having two leaders, one male and one female, to overthrow the patriarchal and confrontational assumptions people make about politics. I don't know, but probably vegetarianism, wool, abolition of magnets (newfangled nonsense!) and the compulsory eating of asparagus. Wait, no, that's cruel - asparagus is people too.
Four parties you may hear about in a historical context:
The SDP - centre-left group who broke away from Labour in the 80s. They allied with the surviving liberals to form the current Lib Dems.
The Fucking Fascists. These were at one point the National Front, and then became the BNP. The BNP are still around, but the latest version is the EDL (English Defence League). They don't like muslims, black people, overly pale people, or people who eat cheese. Mysteriously, the electoral support of the BNP (the EDL are too hip and with it for crusty old things like elections) has plummeted, at exactly the time that support for UKIP rose. UKIP are able to have the same policies as the BNP, but are much more acceptable - BNP candidates are tattooed bald thugs with criminal records, while UKIP candidates are people who laugh a lot, have a lot of teeth, and say "spiffing!", so they're much more electable and it would be rude to suggest that they're fascists.
Respect. A brief left-liberal movement associated with minorities, pacifists and so forth.
The Monster Raving Looney Party. Traditionally the theoretically-amusing protest vote party. Never won anything, and have declined now because its harder to distinguish the lunatics from the serious politicians.
And then there are The Irish...
OK, so what's going on with each party right now?
The Tories: their leader, Theresa May, is the PM. Her policies are deeply unpopular, seen as cruel and austere and out of touch. She has attempted to move her party away from the socially-cuddly, economically-hardline policies of David Cameron, toward a socially-brimstone, economically-protective, more traditional Tory platform designed to appeal to disgruntled UKIP voters. May was assumed to be going to smash the opposition (or Crush the saboteurs! as one newspaper put it), but recent polls show things are NOT going how she hoped, and we're on course for another narrow win, or even a hung parliament. On the other hand, many people will vote for her by default, because that's what you do with Tories - you vote for them, that's what voting is for.
Labour: chaos does not begin to describe it. Their leader, Jeremy Corbyn, is in open war with his own MPs, who are desparate for him to fail. After a rocky start, he caught up to the Tories in the polls, so his MPs staged a political suicide of mass resignations from his cabinet (leaving him with a shadow cabinet of idiots, children and has-beens), which absolutely tanked the party's popularity and brought them to the bring of destruction. They've been gloating about how he'd be brutally crushed this election, allowing them to take control again, but recent opinion polls show them gaining rapidly in the polls.
The root problem is that most of the "PLP" (parliamentary labour party, the actual labour MPs) are from New Labour, a 1990s movement to essentially adopt Tory policies while not actually being the Tories, and rely on everyone hating the Tories. Corbyn, however, comes from Old Labour, the actually left-wing part of the party. The PLP only accidentally let him get elected, and want to change the rules to make sure no left-wing MPs can get elected in future. However, the members of the Labour Party (the 'grassroots') are a long way to the left, and getting further left with every year. As a result, Labour are internally fucked. More on this in an addendum. Externally, their more left-wing brand of policies actually seems to be popular with voters, and they seem to be grabbing a lot of old UKIP voters. They will almost certainly still lose, but it may not be by that much.
The Lib Dems. Having been in coalition with the Tories from 2010 to 2015, the Lib Dems got mullered in the last election. They've, very slowly, been clawing back. Their leader, Tim Farron (an evangelical christian), has moved them back in a more left-wing, socially liberal direction, and is putting everything on opposing Brexit, or at least opposing 'hard Brexit'. This will lose him a lot of votes, but it may also gain him enough disillusioned Remainers from the other parties to grow his own vote share.
UKIP. At death's door. People thought that Brexit might be a breakthrough for them, that they might even take over from Labour. But having achieved their main objective, it seems that their voters are diserting them en masse. Their leader is... some guy. Not Nigel Farage anymore. I don't think? He comes and goes. Since most of them aren't real politicians, they're not very good at all this stuff - they were a one-issue, one-personality-cult party, and they've lost both their issue and their leader. And their only MP defected.
The Greens. Have an MP. Just the one. In Brighton. Brighton is a lovely city. It's the gay capital of the UK, it has a lot of bicycles, and is home to an international beard competition. There's apparently a shop there that sells only CDs with computer-generated artisanal static on them, for the real vinyl experience. [no, seriously, it's a great place. Just not very representative]. Outside of Brighton, the Greens get a small but respectable voter share, but spread out so thinly that they have no real hope of an MP anywhere.
The SNP. Dominate the whole of Scotland, and are the third-biggest party by seats, but not by votes. They have 5% of the vote and 56 seats; the Lib Dems have 8% and 8 seats, while UKIP have 13% of the votes and 1 seat. Their leader is Nicola Sturgeon. She is using Brexit to demand a new referendum on independence.
[confusing things: Scotland does have its own parliament, with powers over certain devolved issues. It also has MPs in Westminster.]
Plaid Cymru. Still exist.
All clear? Any questions? (other than, "what the hell is going on with Labour?")?
But the river tripped on her by and by, lapping
as though her heart was brook: Why, why, why! Weh, O weh
I'se so silly to be flowing but I no canna stay!