Nowadays the use of medical cannabis has been legalized in several large countries, its use as a medical necessity even for recreation is also legalized in some of these countries. Canada for example, you can buy medical marijuana Canada freely if you live there.
Pure Sativa aka pure sativa is very hard to find in the western world, but we are lucky because most of what is in Indonesia is sativa and many are pure sativa. Usually other than Indonesia also from Mexico, Colombia, etc. The plants are tall, thin, with leaves that are better and greener younger. Fast growth, can reach 5 meters in one growing season. When it starts flowering, it will be ready to be harvested when it is 3-4 months afterward. Example: Acapulco, Burmese, and Malawi Gold.
Hybrid or cross-linked sativa means any crossing or strains that are predominantly sativa (more empathetic). Mostly, the physical form is very sativa but the “contents” can mix with indica. Hybrid sativa is usually used for antidepressants and also to increase appetite. Example: Haze, Kali Mist, Jack Herer, Willy Nelson.
Pure indica, usually from hashish producing countries such as Pakistan, Afghanistan, Morocco, Tibet. The plants are short, lush, the leaves tend to be wide and dark with lots of chlorophyll and their growth is very fast. Usually, when it starts flowering, it can be harvested within 2 months after that. Preferably for indoor planting because it is short. Bud aka the flower buds are tight and thick. The most famous is the Afghani strain. It is most narcotic, causes stoning, and has analgesic/pain relieving potential so it is usually used for those things. The example of Indica is relatively pure, a.l: Afghani, Pakistani, Hashplant, Herijuana, Hindu Kush.
Indica hybrid, which is a cross or a dominant strain of indica. Very popular for medical purposes, especially the most famous “Kush”. Preferred by the planters because it is faster to harvest, and preferred by doctors because it is more medically useful, some types: OG Kush, Master Kush, Purple Kush, White Rhino, Romulan, Blueberry, Dutch Treat, Grapefruit, Northern Lights.