Most countries are member of the International Civil Aviation Organization (ICAO) and as such have signed the "Chicago Convention 1944" (111 pages, 2 Mb). Aviation rules and regulations in member countries are based on the recommendations made by the ICAO.
ICAO Annex 2: Rules of the Air, Chapter 3, Table 3.1 describes the VMC minima and cloud distance a pilot must adhere too when flying VFR. The table below shows this in a more comprehensible form.
When the height of the transition altitude is lower than 3050 m (10000 ft) AMSL, FL 100 should be used in lieu of 10000 ft.
|Altitude Band||Airspace Class||Flight Visibility||Distance from Cloud|
|At and above 3050 m (10000 ft) AMSL||A* B C D E F G||8 km||1500 m horizontally, 300 m (1000 ft) vertically|
|Below 3050 m (10000 ft) AMSL and above 900 m (3000 ft) AMSL, or above 300 m (1 000 ft) above terrain, whichever is the higher||A* B C D E F G||5 km||1500 m horizontally, 300 m (1000 ft) vertically|
|At and below 900 m (3000 ft) AMSL, or 300 m (1000 ft) above terrain, whichever is the higher||A* B C D E||5 km||1500 m horizontally, 300 m (1000 ft) vertically|
|At and below 900 m (3000 ft) AMSL, or 300 m (1000 ft) above terrain, whichever is the higher||F G||5 km**||Clear of cloud and with the surface in sight|
* The VMC minima in Class A airspace are included for guidance to pilots and do not imply acceptance of VFR flights in Class A airspace.
** When so prescribed by the appropriate ATS authority:
a) flight visibilities reduced to not less than 1500 m may be permitted for flights operating:
1) at speeds that, in the prevailing visibility, will give adequate opportunity to observe other traffic or any obstacles in time to avoid collision; or
2) in circumstances in which the probability of encounters with other traffic would normally be low, e.g. in areas of low volume traffic and for aerial work at low levels.
b) HELICOPTERS may be permitted to operate in less than 1500 m flight visibility, if manoeuvred at speeds that will give adequate opportunity to observe other traffic or any obstacles in time to avoid collision.
Except when operating as a special VFR flight, VFR flights shall be conducted so that the aircraft is flown in conditions of visibility and distance from clouds equal to or greater than those specified in the table above.
Except when a clearance is obtained from an air traffic control unit, VFR flights shall not takeoff or land at an aerodrome within a control zone, or enter the aerodrome traffic zone or traffic pattern:
a) when the ceiling is less than 450 m (1500 ft); or
b) when the ground visibility is less than 5 km.
VFR flights between sunset and sunrise, or such other period between sunset and sunrise as may be prescribed by the appropriate ATS authority, shall be operated in accordance with the conditions prescribed by such authority.
Unless authorized by the appropriate ATS authority, VFR flights shall not be operated:
a) above FL 200
b) at transonic and supersonic speeds.
Authorization for VFR flights to operate above FL 290 shall not be granted in areas where a vertical separation minimum of 300 m (1000 ft) is applied above FL 290.
Except when necessary for takeoff or landing, or except by permission from the appropriate authority, a VFR flight shall not be flown:
a) over the congested areas of cities, towns or settlements or over an open-air assembly of persons at a height less than 300 m (1000 ft) above the highest obstacle within a radius of 600 m from the aircraft;
b) elsewhere than as specified in 4.6 a), at a height less than 150 m (500 ft) above the ground or water.
Except where otherwise indicated in air traffic control clearances or specified by the appropriate ATS authority, VFR flights in level cruising flight when operated above 900 m (3000 ft) from the ground or water, or a higher datum as specified by the appropriate ATS authority, shall be conducted at a cruising level appropriate to the track as specified in the tables of cruising levels in Appendix 3.
Based on: ICAO Annex 2: Rules of the Air, Chapter 3, Table 3.1. Read the full details in the original Annex 2 here.
Remember that each country can and does apply changes to the standard ICAO VMC Minima, so be sure to check the most current relevant AIP.