What is ketones and nomenclature ? …

The IUPAC system of nomenclature assigns a characteristic suffix of -one to ketones. A ketone carbonyl function may be located anywhere within a chain or ring, and its position is usually given by a location number. Chain numbering normally starts from the end nearest the carbonyl group. Very simple ketones, such as propanone and phenylethanone do not require a locator number, since there is only one possible site for a ketone carbonyl function. The common names for ketones are formed by naming both alkyl groups attached to the carbonyl then adding the suffix -ketone. The attached alkyl groups are arranged in the name alphabetically. 

Ketone Nomenclature rules:-

Ketones take their name from their parent alkane chains. The ending -e is removed and replaced with -one.
The common name for ketones are simply the substituent groups listed alphabetically + ketone.
Some common ketones are known by their generic names. Such as the fact that propanone is commonly referred to as acetone.