I have a keen interest in learning new things about whatever technology I am using at work and then sharing my knowledge and experiences with colleagues.
One of my friends has repeatedly told me NOT to share knowledge with colleagues because this will give me competition in the subject-matter. He indicated that if the team lead wants to select a particular person for a task, I might be passed over for this project in favor of a colleague, who may have learned the subject-matter originally from me.
But from my point of view, having others besides me know the same subject matter makes a better, more productive working environment.
Will sharing knowledge create trouble for me at appraisal time if others gain an edge over me because of the new knowledge I gave them?