Article 8. Grave felonies, less grave felonies and light felonies. —  Grave felonies are those to which the law attaches the capital punishment or penalties which in any of their periods are afflictive, in accordance with Art. 25 of this Code.

 Less grave felonies are those which the law punishes with penalties which in their maximum period are correctional, in accordance with the above-mentioned Art..

Light felonies are those infractions of law for the commission of which a penalty of arrest menor or a fine not exceeding 200 pesos or both; is provided. (Revised Penal Code)

What is the significance of classifying felonies into grave, less grave or light felonies?

To determine:

1.  Whether a complex crime was committed;
2.  The duration of subsidiary penalty to be imposed;
3.  The duration of the detention in case of failure to post the bond to keep the peace
4.  Whether the crime has prescribed;
5.  The proper penalty for quasi-offense.