People are born female or male but learn to be girls and boys who grow into women and men. This learned behaviour determines our gender roles. Sex refers to those characteristics which are biologically-determined. The word gender is used to describe those characteristics of women and men, which are socially-constructed. Gender equality means equal treatment of women and men in laws and policies, and equal access to resources and services within families, communities and society at large - an absence of discrimination on the basis of a person’s sex in opportunities and the allocation of resources or benefits or in access to services.
gender equity - means fairness and justice in the distribution of benefits and responsibilities between women and men. The concept recognizes that women and men have different needs and power and that these differences should be identified and addressed in a manner that rectifies the imbalance between the sexes. It often requires women-specific programmes and policies to end existing inequalities. 
gender discrimination - any distinction, exclusion or restriction made on the basis of socially constructed gender roles and norms which prevents a person from enjoying full human rights. 
gender sensitivity - is recognizing the differences, inequalities and specific needs of women and men and acting on this awareness 
gender analysis - is a process of gathering information by sex, often referred to as sex-disaggregated data 
gender planning - is a process of applying the results of gender analysis to bridge the gaps identified 
gender mainstreaming - is a process of consistently incorporating a sensitivity of gender differences in policy, planning, budgeting, and implementation of programmes and projects in order to overcome inequalities between men and women, boys and girls. Gender mainstreaming in health has the potential to transform existing policies and health delivery services into those that will ensure that no one is denied their fundamental right to health on account of gender. 
In response to the 1995 Beijing Platform for Action, the Economic and Social Council (ECOSOC) of the United Nations accepted a definition of mainstreaming gender as "...the process of assessing the implications for women and men of any planned action, including legislation, policies or programmes, in any area and at all levels. It is a strategy for making women’s as well as men’s concerns and experiences an integral dimension in the design, implementation, monitoring and evaluation of policies and programmes in all political, economic and social spheres, such that inequality between men and women is not perpetuated. The ultimate goal is to achieve gender equality"
At the World Health Organization: "the term gender mainstreaming is a short-hand way of referring to the strategies and processes that can change the way that institutions operate in relation to the power and privilege that is associated with things done by and for men and women. We use the word “mainstream“ to indicate that issues of gender inequality should be dealt with in every aspect of organizational structure and programming, rather than as a separate, add-on activity. In other words, gender inequality should be addressed in the mainstream of an organization and programming. The full phrase should be: “mainstreaming attention to gender equalities in institutional structures and their programming.“" 
"Mainstreaming gender is both a technical and a political process which requires shifts in organisational cultures and ways of thinking, as well as in the goals, structures and resource allocations .... Mainstreaming requires changes at different levels within institutions, in agenda setting, policy making, planning, implementation and evaluation. Instruments for the mainstreaming effort include new staffing and budgeting practices, training programmes, policy procedures and guidelines"
At the WHO, gender analysis " identifies, analyses and informs action to address inequalities that arise from the different roles of women and men, or the unequal power relationships between them, and the consequences of these inequalities on their lives, their health and well-being. The way power is distributed in most societies means that women have less access to and control over resources to protect their health and are less likely to be involved in decision making. Gender analysis in health often highlights how inequalities disadvantage women’s health, the constraints women face to attain health and ways to address and overcome these. Gender analysis also reveals health risks and problems which men face as a result of the social construction of their roles".
Health Canada has a policy of gender-based analysis: “Gender-based analysis is an analytical tool. It uses sex and gender as an organizing principle or way of conceptualizing information - as a way of looking at the world. It helps to bring forth and clarify the differences between women and men, the nature of their social relationships, and their different social realities, life expectations and economic circumstances. It identifies how these conditions affect women’s and men’s health status and their access to, and interaction with, the health care system. “ 
3. Issues Paper, ECOSOC Panel Discussion on "Gender Mainstreaming in the United Nations operational activities" July 2, 2004. www.un.org/esa/coordination/ecosoc/Intergovtal_panel_22Jun.pdf accessed January 25, 2006
4. Director-General's Executive Statement on WHO Gender policy: Integrating Gender Perspectives into the Work of WHO. World Health Organization, 2002. whqlibdoc.who.int/hq/2002/a78322.pdf accessed January 25, 2006