Cannabis is often categorized as Sativa and Indica. However, this classification is neither clear nor really useful.
Widespread classification into Sativa and Indica
The fairly widespread classification of cannabis plants into the two types Cannabis Sativa and Cannabis Indica is based on many different criteria.
One factor is the physical and botanical nature of the plant. Sativa plants are basically taller and slimmer, while Indica plants grow smaller and bushier. Sativa leaves are also thinner and have longer “fingers”, while indica leaves are a darker shade and wider.
The larger sativa plants also have a longer growing and flowering period.
Sativa stimulates, indica calms?
In addition to these botanical differences, which have been greatly softened by various “hybrid varieties,” or hybrids of the two types, the classification is based primarily on alleged differences in effect.
The sativa varieties are said to have a stimulating effect: consumption provides an energy boost and promotes concentration. Indica varieties, on the other hand, would have a calming effect. Accordingly, Sativa is recommended during the day and Indica at night.
However, this classification is based almost exclusively on anecdotal experience and defies scientific fact.
Irrelevant is the classification from a legal perspective: All cannabis plants are varieties of the plant Cannabis Sativa L.. 
Indica and Sativa in science
The botanical differences between sativa and indica plants can be well justified in principle. However, this classification is (increasingly) quite useless, since very few plants can be clearly assigned to a type. There are also botanists who divide the plant into up to four types: cannabis sativa, cannabis indica, cannabis ruderalis and cannabis afghanica.  In the end, however, this is not very important: anyone who wants to grow hemp should know about the individual variety, how it grows and what its advantages are – regardless of whether it is now called sativa or indica.
The situation is similar with the allegedly different effects of the various types. There are no studies that demonstrate the differences in effect or CBD and THC content to a relevant extent. Another reason to say goodbye to the “sativa vs. indica” type classification.
So the type distinction is rather meaningless, or even misleading, from the consumer’s point of view: the differences in the content of cannabinoids (CBD, THC, CBG, …) and terpenes are huge from variety to variety, regardless of type.  These chemical differences in terms of active ingredient content are also what actually influence the effect. Therefore, if there is a need for one, the division into “chemotypes” makes much more sense: there are varieties that contain mainly THC, varieties with THC & CBD, and CBD-heavy varieties.
The discussion about the sense and nonsense of the classification into Cannabis Sativa and Cannabis Indica very quickly takes on scientific features that are irrelevant for consumers. There is a strong case for abandoning the widely used classification: The classification is unclear, sometimes even wrong, and leaves out important information. From the consumer’s perspective, it is important – especially in the medical field – that a complete cannabinoid and terpene profile is established and communicated for each individual plant. Only in this way can the effect be reliably estimated in combination with experience and scientific evaluations.