Standards are detailed, officially approved documents that may be rules, testing methods, definitions, recommended practices, and specifications that promote uniformity. They ensure that products and services meet minimum thresholds and cover areas such as quality, performance, design, safety and environmental impact for engineering design, industrial practices, and terminology, etc.
This presentation from the National Standards Authority of Ireland (NSAI) gives some background information on standards and eurocodes.
Many Irish standards are developed nationally or adapted from European and international standards
Find them on the British Standards Online under their BS EN number. There is a list of the Eurocodes, their corresponding BS EN numbers and the British Standards they superseded at Eurocodes Expert
Note: In some cases there may be a National Annex which define criteria for a particular State. In these cases the National Standard, which contains the National Annex for that State, should be used. An example of this is the Eurocodes which have requirements set down in the National Annexes.
Various agencies and organizations issue standards so they can be tricky to locate. They are updated irregularly and the newest version may not be the one cited in a reference. They may be withdrawn or superseded by another standard with a different name.