When to use anonymous link?

When should I use anonymous web link and when personalized links?

Anonymous links don’t have the ability to individually track by respondents.
This may be necessary if you (for example) publish the link on a website, or post however it is not ideal. Unless you have other controls (cookies, email capture etc) there is no way to prevent multiple participation by the same person. In addtion, auditability is compromised.

Personalised links track the ID of the participant into the survey and on exit. They require some more setup but give one more control over tracking and auditing respondent sampling.