The Canary Islands lie to the northwest of the African coast, by Morocco-occupied Western Sahara. They are presently an autonomous region of Spain and are in the Greenwhich Mean Time Zone (same time as Great Britain and Portugal).
The islands are volcanic in origin and have a few dormant volcanos but none that are presently dangerous.
The islands were inhabited since the times of the Roman Empire by people with stone-age technology, known collectively as the guanches. The Spanish Crown of Castile gained control of them in the 15th c., through conquest. French people like Bethencourt and his men, plus (a bit later) many Spaniards, were involved in the conquest.
The islands then received many settlers and traders, from Spain, Portugal, Genoa, Flanders, France, England, etc. These, plus the surviving aboriginal people and slaves brought from Northwest Africa and West Africa all mingled to form a rather homogenous, European-looking society, though modern sympathies lean very heavily towards the Aborigin side. Around the mid-20th century many islanders emigrated to places like Cuba and Venezuela, so it's possible to see South-American influences around.
There are 7 main islands in the archipelago, from east to west: Lanzarote, Fuerteventura, Gran Canaria, Tenerife, La Gomera, La Palma and El Hierro.
All are different but, generally speaking, those closest to Africa are drier, especially Lanzarote and Fuerteventura. The rest, being more mountaneous, tend to have a greener side, where the clouds brought by the Trade Winds accumulate against the mountains, and a drier side, where most tourist resorts concentrate.
The weather changes according to area and season but is generally mild year-round. Summer temperatures are usually in the high 20s Celsius, with short drier, hotter (30-40ºC), periods resulting from duststorms in the Sahara. Winter temperatures by the coast are mild, around 20ºC. Towards the mountains it gets colder and can even snow (in the highest parts in cold years).
If this surprises you, think that the highest mountain in Spain is in Tenerife, with an altitude of 3,718 metres (over 12,000 feet). Several other islands have peaks around the 2,000m (6,500ft) mark. The islands are not large so the slopes and changes tend to be steep.
The islands are connected by plane (not cheap) and various types of ferry (cheap, rides usually take a few hours).
Some links that might be of interest: