A homologous series is a collection of organic compounds with the same general formula and the same functional group. The members of a homologous series have nearly identical chemical properties due to the same functional group, and they show a gradual increase in the values of physical properties. Some examples of homologous series are alkane, alkene, alcohol, carboxylic acid, aldehyde, ketone, etc. The characteristics of a homologous series are:

• They contain the same functional group throughout the series.
• The members of the homologous series can be prepared by the same general method.
• They show a gradual increase in the values of physical properties.
• Two adjacent members differ by one $CH_2$ group, and the mass of a higher homologue is greater by 14g than an adjacent lower homologue.

It is important to note that homologous series are commonly studied in organic chemistry and are part of the CBSE Class 10 Chemistry curriculum.