Diversity
Diversity is the full range of salient differences between people in a group such as a team, company, or governing body. Aspects of diversity can include cohorts of education level, life experiences, abilities, race/ethnicity, sex, gender identity, sexual orientation, age, physical/mental health, or other demographic traits.
A simple metaphor to understand diversity is that diversity means "having a seat at the table."
A group is considered "diverse" when it has representation from each cohort in the same proportions as the larger group it belongs to. For example, a team in a department at a company should reflect the cohorts within the department, which should reflect the cohorts within the company, which should represent the cohorts within the society it is part of.
Broader Topics Related to Diversity
Social Justice
The balance of opportunity and wealth distribution in a society
Equity
The opportunity for fair representation within a group