CBD oils are intended for sublingual (under the tongue) use or by oral ingestion - by swallowing the liquid.
It is made by separating the CBD with a nutrient-quality oil, for example MCT oil is mixed.
A transporter oil like MCT oil is required because CBD is fat-soluble. This implies that it breaks down into fat rather than water and allows the body to store it in adipose tissue.
Spending CBD alongside fat increases the bioavailability of CBD oil.