The Scottish equivalent of the English parish registers have been searchable online at www.scotlandspeople.gov.uk for some time now, but the website has now added images of the pages. This is a major enhancement of the service for anyone with Scottish ancestry.
The earliest existing OPR is from Errol in Fife in 1553, but in most parishes the OPRs only begin in the mid to late 1600s, or the early 1700s. In remote areas, such as the Outer Hebrides, it’s common to find that the start date for the OPRs was the early 1800s. However, the most important thing to realise about these records is that, largely, they relate only to people who were members of the Established Church of Scotland (ECoS).
Your Family Tree has an article that describes the records and tells how to use the new online service. You can read the article at http://www.yourfamilytreemag.co.uk/page/yft?entry=scottish_parish_record_images_go