There are several different sorts of experience that postdocs can have:
• Postdoctoral research posts - funded on larger project or programme grants – you apply to the principal investigator in a lab for a job on a short-term contract
• Personal Fellowships - long established, prestigious awards that provide a more robust route for those aspiring to become independent researchers – you apply to a funding body for your own fellowship and to a lab for space to work
• Postdoctoral posts in Research institutes – where there may be opportunities for career progression – MRC, Cancer Research UK and the Wellcome Trust, for example, employ salaried staff in their own institutes
• Overseas – you can spend 2 or 3 or more years working in a lab abroad, funded either through a grant to the lab or by a personal fellowship.