“The term is most common in biochemistry, where it is a synonym of saccharide (from Ancient Greek σάκχαρον (sákkharon) ‘sugar'[1]), a group that includes sugars, starch, and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides and disaccharides, the smallest (lower molecular weight) carbohydrates, are commonly referred to as sugars.[2] While the scientific nomenclature of carbohydrates is complex, the names of the monosaccharides and disaccharides very often end in the suffix -ose, which was originally taken from the word glucose (from Ancient Greek γλεῦκος (gleûkos) ‘wine, must’), and is used for almost all sugars, e.g. fructose (fruit sugar), sucrose (cane or beet sugar), ribose, lactose (milk sugar), etc.”*
Carbohydrates or “carbs” for short, are basically a rapid, sugar based energy source for our bodies. Rapid because our system can convert them to calories very efficiently depending on the complexity of the “sugar” molecule that they provide.
*https://en.wikipedia.org/wiki/Carbohydrate