Professional testers should confirm their knowledge by a certificate. There is a very good certification roadmap which is accepted throughout the world - ISTQB (International Software Testing Qualifications Board). For now ISTQB has issued over 240.000 certifications in more than 70 countries world-wide.
ISTQB offer three levels of certification: Foundation, Advanced and Expert, there are also a few specialization on each level (except Foundation Level) like Test Manager or Test Automation. Full roadmap you can see above.
