What is the theory of acquired character?

The theory of acquired characters says that traits gained during life can be passed to the next generation. This theory was given by Jean-Baptiste Lamarck. He believed that if an organism changes during its lifetime due to use or disuse of organs, these changes are inherited by its offspring. 

For example, Lamarck said giraffes developed long necks by stretching to reach high leaves, and this change was passed on. Modern science has shown this theory is not fully correct. Traits passed to offspring are usually due to genes, not life experiences. However, Lamarck’s ideas were important in starting the study of evolution.