Tell me about the botanical garden?

A botanical garden have a collection of living plants for the purpose of scientific research, conservation, display, and education. Plants are labelled with their botanical names. It may contain specialist plant collections such as cacti and other succulent plants, herb gardens, p tropical plants, alpine plants, or other exotic plants.
The origin of modern botanical gardens is generally traced to the appointment of professors of botany to the medical faculties of universities in 16th century Renaissance Italy, which also entailed the curation of a medicinal garden.
Botanical gardens are often run by universities or other scientific research organizations. The staff will normally include botanists as well as gardeners. 
Worldwide, there are now about 1800 botanical gardens and arboreta in about 150 countries (mostly in temperate regions) of which about 550 are in Europe (150 of which are in Russia), 200 in North America, and an increasing number in East Asia. These gardens attract about 300 million visitors a year.