What climbs, trails or makes useful ground cover, comes in different shapes and colours, is evergreen, hardy and happy in shade? Only the ivies (or hedera to give the genus name) have such a combination of attributes.
Contrary to common belief, there are hundreds of varieties of hedera, large and small, an assortment of leaf shapes and many are variegated. Hedera are not the poison ivy, which is Toxicondendron radicans, and you will have to search for a case of true ivies doing any harm. Furthermore, they do not damage walls in good condition.
The ivies are sadly under-rated plants which can be included with considerable advantage in almost every garden.
If you really want to study ivies you need Peter Rose's book but for some notes on nomenclature, botany, cultivation and selected clones follow the link below.