Delta-8-tetrahydrocannabinol (Δ8-THC) is the isomer of Delta-9-tetrahydrocannabinol (Δ9-THC), in which the double bond in the cyclohexene ring is located in a different position, making the molecule more stable than Δ9-THC and less prone to conversion into cannabinol (CBN) over time.
Recently Δ8-THC became particularly attractive because of its ability to generate a similar, but less potent psychoactive effect than Δ9-THC and for its boosted shelf life capability.
Δ8-THC is found in low percentages in cannabis plants and commercial processors usually resort to selective breeding, distillation and chromatographic isolation to create concentrates that are rich in Δ8-THC.  Once isolated, this cannabinoid is an extremely viscous oil at room temperature, but nowadays it can be sold in many different forms and products: distillate cartridges, oil, tincture, edibles, beverages, Δ8 distillate infused flowers and cannabis varieties containing high levels of Δ8.
Weather the user will ingest, smoke or vape Δ8 containing products, the effects will be similar to its related Δ9 isomer, with less pronounced psychotropic effect and beneficial antiemetic, anxiolytic, orexigenic, analgesic and neuroprotective therapeutic properties. 
Because of increased absorption rate through inhalation, Δ8 vape cartridges, Δ8 cannabis chemovars or Δ8 -coated flowers are particularly suitable to feel immediately the cannabinoid effects.
Within edibles, Δ8 gummies are really popular for those who don’t like to inhale smoke or use tinctures: created by infusing Δ8-distillate with gum candy, they offer an easy way of dosing the active compound and they have much longer shelf life than similar cannabis-infused products. 
Some manufacturers started to produce Δ8-THC in the laboratory, treating cannabidiol (CBD) with heat and acids: the possibility of contaminants from solvents and reagents accumulating in the final product of this chemical reaction are an actual concern for people health. It is recommended to always consult the certificate of analysis (CoA) of Δ8 products intended to be used in order to check the composition and the contaminants threshold limits.