A "cookie" is a small data-file which is written to a specified space on your hard drive. It can contain various information necessary to make the service more available and usable. Cookies have varying lifespan; either per session or persistent.
You have the option to turn off this feature and remove previous cookies in your browser configuration. Of course the desired functionality will then also be lost. Some browsers provide a certain mode of browsing, often called private or incognito mode, which automatically removes all temporary data (including cookies) when you close the browser window.
Cookies on Hapfind
For users who solely uses the service for finding events and happenings the only cookies which are stored are used to see how the site is being used and to recognize parts of the website which needs to be improved.
Additional cookies are stored for users who has a user account for advertising via the service. The cookies contain data which allows you to navigate between parts of the website without being required to log in every time you move from one place to another.