The Cub Scout Leader’s Book gives an outstanding answer to this question. It states:

Cub Scouting is a program of the Boy Scouts of America (BSA), whose overall mission is to help young people build character, learn citizenship, and develop personal fitness. While the BSA serves boys from ages 7 through 20 and girls from ages 14 through 20, Cub Scouting focuses on boys in the first through fifth grades (or from ages 7 through 10). (p. 9) 

The history of Cub Scouting goes back to 1914 when Lord Baden Powell, the founder of Boy Scouts, started implementing a program for younger boys who were interested in becoming Boy Scouts. Two years later, the Wolf Cubbing program began in England. The Cub Scouting program or Cubbing program as it was called until 1945 when the name was changed to Cub Scouting, did not come to America until 1930.

The program takes many of its ideals from Rudyard Kipling’s Jungle Book and from the American Indian heritage.

The terms "Law of the Pack," "Akela," "Wolf Cub," "grand howl," "den," and "pack" all come from the Jungle Book. At the same time, the Gold and Silver Arrow Points, Webelos emblem, and Arrow of Light emblem are taken from our American Indian heritage. (History of Cub Scouting)

Cub Scouts live by three guiding principles or ideals. They are the Cub Scout Promise, the Law of the Pack, and the Cub Scout Motto.

In the Cub Scout Promise, scouts promise to do their best, to do their duty to God and their country, to help other people, and to obey the Law of the Pack.

The Law of the Pack gives the scouts a law or rule to follow. The Law of the Pack essentially tells scouts to follow the directions given to them by their parents, den leaders, and other adults. It also tells them to be an active participant in the pack and the pack will help the scouts grow and develop. Finally, the Law of the Pack tells the scouts to provide service to others.

The Cub Scout Motto is “Do Your Best”. It is important for scouts to realize that they do not have to be perfect instead, they need to do their best in all the things they do. The Cub Scout Leader Book explains the Cub Scout Motto in the following way:

Doing your best is one of the most important things Cub Scouts learn. When boys compare themselves to other people, they can become complacent (if they’re high achievers) or discouraged (if they have to work harder to accomplish the same goals). Focusing on doing their personal best helps, them feel good about themselves and see their potential for doing even better. (p. 12)

The Cub Scouting program is designed to prepare boys for Boy scouts and life by building character; teaching scouts how to become good citizens, and developing personal fitness.

The program uses twelve core values to develop character in the scouts. The core values are citizenship, compassion, cooperation, courage, faith, health and fitness, honesty, perseverance, positive attitudes, resourcefulness, respect, and responsibility.

Each month, scouts focus on one of the twelve core values. During their den meetings, scouts will be taught the core value and learn how to apply it to their own lives. At least once a month, scouts will go on an outing that relates to the core value being studied that month. Learning about the monthly core value culminates at the monthly pack meeting where the scouts display what they have learned during the month.   

Cub Scouts develops boys to become active citizens in their community. Cub Scouts develop good citizenship when they are learning about respecting the flag and providing service to the community.

The Cub Scouting program teaches personal fitness. Scouts personal fitness is developed through participation in den and pack activities, the outdoor program, the academic and sports program, and the BSA Family program.

The Cub Scout Leaders Books states:

Cub Scouting activities are designed for boys who are in the normal range of development, but the program is flexible enough to adapt to the needs of boys who are developing faster or slower than their peers or who face physical, mental, or emotional challenges. (p. 21)

Cub Scouting offers a yearlong program for boys in the first through fifth grades to help them grow and develop into young men.