"Service" refers to the delivering of the document to the Respondent. This can be done by Personal Service (delivering hard copies of the document physically to the Respondent), by Registered Post to their last known residential or registered address or ACRA registered address (for businesses), or by any other means as directed by the ECT.

For more information, you may visit https://www.judiciary.gov.sg/civil/how-to-file-serve-employment-claim - under the "How to file and serve" section.