Introduction
I was inspired to start this when I was reading through the site and found that the vast majority of firearms articles assumes United States laws. I live in Canada, and I know there are members from around the world. This is a W.I.P. If you know about gun laws and find something wrong, please fix it! If something is missing, please add it! Adding other countries would be nice, as well! Thank you.

The countries are listed in alphabetical order (sorry Americans, it's officially the United States). *These are notes for potential editors* Links to more information are provided whenever possible.

Australia
In Australia, state laws govern the possesion and use of firearms. They were mostly aligned under the 1996 National Agreement on Firearms. To possess or use a firearm, you must have a Firearms License and (usually) be over the age of 18. Owners must store firearms securely. Before one can buy a firearm, he/she must get a Permit To Acquire. There is a mandatory 28-day delay before it is issued. For each firearm a "Genuine Reason" must be given. Pest control, hunting, target shooting and collecting are valid reasons. Self-defense is not accepted as a reason for issuing a license, though it may be legal to use a firearm for that purpose under some circumstances. Each firearm must be registered to the owner by serial number.
Firearms are divided into Categories:
-Category A: Rimfire rifles (not semi-automatic), shotguns (not pump-action or semi-automatic), air rifles and paintball markers
-Category B: Centrefire rifles (not semi-automatic), non-antique muzzleloading firearms
-Category C: Semi-automatic rimfire rifles holding less than 10 rounds, pump-action or semi-automatic shotguns holding less than 5 rounds
-Category H: Handguns, including air pistols, deactivated handguns and guns less than 65 cm long (target shooters are limited to .38 caliber or less) (barrels on semi-automatic handguns must be >4.72" long, >3.94" for revolvers)
-Category R/E: restricted weapons, including but not limited to machine guns, flamethrowers, assault rifles, and anti-tank guns -Antique: single-shot muzzleloading firearms made before 1901, some antique revolvers and repeating firearms

Category C and Category D firearms are more difficult to acquire. For Category C, you must be a primary producer, occupational shooter, collector, or clay target shooter. For category D, you must be an occupational shooter, though collectors can acquire deactivated Category D firearms.

http://en.wikipedia.org/wiki/Gun_politics_in_Australia

*Would someone from Australia or at least familiar with their laws check this over? Also, how hard is it to get a Category H firearm?"

Canada
In Canada, the license required is called a Possesion and Acquisition license. To acquire a non-restricted PAL, one must be over the age of 18 and pass the CFSC (Canadian Firearms Safety Course). Those under the age of 18 but over the age of 12 may acquire a Minor's License, which allows that person to borrow a firearm and buy ammunition.

There are three classes of firearm in Canada, each with its own type of license.
1. Non-Restricted: Most semi-automatic and manual action rifles and shotguns.
2. Restricted: Most handguns and some restricted semi-automatic rifles and shotguns.
3. Prohibited: Fully automatic weapons and firearms prohibited by name.

To acquire a restricted PAL, one must also pass the Canadian Restricted Firearms Safety Course. To purchase a firearm, you must be member of a certified range. An Authorization To Transport is required to purchase a restricted firearm as well. Getting a prohibited PAL is practically impossible. All firearms in Canada must be registered to the National Firearms Registry.
Semi-automatic rifles and shotguns have a maximum magazine capacity of five rounds. Some rifles, such as the M1 Garand, are exempted by name. There is no restriction on manual-action rifles or shotgun or rimfire semi-automatic rifles. All handguns have a maximum capacity of ten rounds. Removable bullpup stocks and silencers are both prohibited.

http://en.wikipedia.org/wiki/Gun_politics_in_Canada
http://www.rcmp-grc.gc.ca/cfp-pcaf/pol-leg/hl-fs-eng.htm

*Examples of non-restricted, restricted and prohibited firearms would be appreciated*

China
Chinese citizens can purchase airguns with caliber no greater than .177 (4.5 mm). Private citizens cannot purchase or possess firearms.

*Is this true? It's hard to find information, though I'm sure it's out there.*

France
There are three categories of gun owners- private citizens, hunters, and target shooters belonging to the French Shooting Foundations (Federation Francaise de Tir).

There are six classes of firearm:
Class 1: Any centrefire handgun or long gun in a designated military caliber.
Class 4: Defense firearms. Revolvers, pistols or non-military calibre, short rifles, semi-automatic rifles with more than three rounds capacity, repeater rifles with more than ten round capacity, riot guns (shotguns? less lethal guns?) with over five-round capacity, military lookalikes or disguised weapons.
Class 5: Hunting arms, including shotguns (including semi-automatics with less than 3-round capacity), riot guns with a 5-round limit, repeating rifles in non-military calibre with less than 10-round magazine capacity, and semi-automatic rifles in a non-military calibre with a 3-round capacity and non-removable magazine. Total length must be over 80cm and barrel length over 45cm.
Class 6: Blades and any weapon that could be a threat to public safety. Not firearms. A stone is a stone but carried in a crowd the the intent to throw at someone would be a Class 6 weapon. Mace and such sprays are in this category, and availible to buy, but not carry.
Class 7: Rimfire single shot and repeating rifles, air guns, single shot .22 pistols with a length of over 22 centimetres. Class 8: All guns and copies made before 1870 and not using metallic cartridges. All deactivated guns.

Category 5, 6, 7, and 8 weapons may be bought by any private citizen with no firearms certificate. The buyer's name and address is registered for the Class 5 and Class 7. Break-action shotguns need not be declared at all. On a firearm certificate renewable every five years, the private citizen is allowed to have one handgun in non-military calibre for home defense, with only a background check required.

A hunter may acquire a fourth category gun, such as a semi-automatic rifle with removable magazine (in non-military calibre) or short-barreled bolt-action rifle. To be classified as a hunter, one must be over the age of 16 (not 18 like for the private citizen) and pass an exam on wildlife, gun handling and safety. A "permis de chasse" is then issued for life.
Only an accredited target shooter and member of the FFTir is allowed to have a first category firearm. They must be a member of a shooting club and there is a six-month probational period. They are allowed to buy and own up to seven first and fourth category weapons and can buy up to a thousand cartridges a year. The license is renewed every three years.

http://www.survivalistboards.com/showthread.php?t=10150

*I could literally find one source for this information, one that is probably unreliable. If someone would check it over and correct it, that would be great. I imagine it would be much easier to find information if I could read French!*

Germany
In Germany the possession of any firearm with a fire energy exceeding 7.5 Joule requires a valid firearms ownership license for any particular weapon. The current Federal Weapons Act adopts a two-tiered approach to firearms licensing.

A firearms ownership license (Waffenbesitzkarte) must be obtained before a firearm can be purchased. A license is necessary for EACH firearm. On public premises, a licensed firearm must be unloaded and transported in a stable, fully enclosing, locked container. Firearms licenses are valid for three years or less. Insurance and a means to securely store the weapon is mandatory. One must meet certain criteria, such as being over the age of 21 (18 for rimfire calibers) and having a reason to acquire the gun. Convicted felons, those with a history of mental disorder, and those who are deemed unreliable (such as those with drug or alcohol addictions) cannot acquire a license.

In Germany, there are also firearms carry permits. A carry permit allows the licensee to publicly carry legally owned weapons, loaded and concealed or non-concealed. A mandatory legal and safety class and shooting proficiency tests are required. A carry permit is generally only issued to those who need to carry a firearm, such as security guards or licensed hunters.

http://www.bmi.bund.de/cln_145/DE/Themen/Sicherheit/Waffenrecht/waffenrecht_node.html (German) http://en.wikipedia.org/wiki/Gun_politics_in_Germany
*What types of weapons are prohibited, and do some require special licenses?*

Japan

Japan prohibits gun possession by citizens except for shotguns and single-shot rifles for hunting or sports. Semiautomatic and full automatic weapons are restricted to military and police. Gun owners must take a class once a year and pass a written test. Police check on the owner once every three months on an unannounced visit. They inspect the gun locker, proper ammunition storage, and the firearm.

Russia
In Russia, one may buy smoothbore shotguns, gas pistols, or revolvers shooting rubber bullets, with a license. After five years, one may purchase a rifle or carbine.
*Really needs more details. Like, a lot more details.*

United Kingdom
All firearms in the UK must be licensed on either a firearm certificate (FAC) or a shotgun certificate. A shotgun is defined as having a barrel no shorter than 24”, a bore not larger than 2”, no revolving cylinder, and a maximum 2-round magazine. Shotguns with a larger capacity are subject to a firearm certificate. It is somewhat easier to acquire a shotgun certificate.

A firearm certificate requires justification for each gun. Each firearm is listed on the certificate, with type, calibre, and serial number. To obtain a certificate, the police must be convinced that the owner has good reason to own the gun and that the owner will be able to use it "without danger to the public safety or to the peace". Self-defense is not considered a valid reason.

*Could someone put the requirements here, please? Thanks! Also, what guns are legal and what guns are not?*

United States

Each state in the country has different regulations for firearms. This makes it complicated to state all on one page. To find out information on each state, check this link here.