An alkyl is a univalent (or monovalent) chemical group derived from an alkane by removing one hydrogen atom. It is often represented by the symbol "R".

Alkyl groups are part of organic molecules. They consist of carbon and hydrogen atoms arranged in a chain, with a general formula of C_nH_2n+1, where 'n' is the number of carbon atoms. Alkyl groups are not stable on their own and are always bonded to other atoms or groups within a molecule.

Examples of alkyl groups include:

• Methyl (CH₃): Derived from methane (CH₄).
• Ethyl (C₂H₅): Derived from ethane (C₂H₆).
• Propyl (C₃H₇): Derived from propane (C₃H₈).
• Butyl (C₄H₉): Derived from butane (C₄H₁₀).

Alkyl groups are important in organic chemistry because they form the "backbone" of many organic molecules and affect the properties and reactivity of these molecules.

For more information you can refer to:

• UCLA's document on alkanes
• Organic Chemistry Tutor