New EU laws come in to effect at midnight which give consumers greater protection if they purchase goods on the internet within the European Union.
They include the right to quicker refunds, reduced from 30 days to 14 days.
Online traders will also be obliged to show total costs on screen rather than adding hidden ones to a credit or debit card bill.
Grace Duffy of the European Consumer Centre in Dublin said online consumer rights would improve as a result.
"Certain existing rights have been extended, including the right of withdrawal whereby a consumer can return a product within seven days of receiving it. That has been extended to digital purchases for the first time," she said.
"So, consumers who buy books or music in digital format will be able to change their mind and return the product for a refund, up until the moment the downloading process begins.