"Standards are agreed ways of doing something, written down as a set of precise criteria so they can be used as rules, guidelines or definitions". (BSI/British Standards Institution)
Standards are applied to many materials, products, methods and services, and are cretaed by industry experts to share best practice. They are designed for voluntary use and do not impose any regulations. However, laws and regulations may refer to certain standards, making compliance with them compulsory.
Health and Safety standards aimed at workplace safety are a well known example, but you will find standards operating across many activities of daily life, for example IT standards to keep data safe, food safety standards to protect against contamination, engineering standards to ensure consistency, quality and compatibility across manufactured materials and many more.
The standards are laid out in a published specification that establishes a common language and an agreed, repeatable way of doing an activity or process.
Standards are designed for voluntary use, and do not impose any regulations.
However, laws and regulations may refer to certain standards and make compliance compulsory.
Observation of certain standards is often a requirement in order to comply legally with a contract.
Specification: highly prescriptive; the detailed absolute requirements for a product, material, process, service or system, and the procedures for checking conformity; the most commonly used standard.
Method: highly prescriptive; an agreed way of measuring, testing or specifying what is reliably repeatable in different circumstances and places
Guide: advice which reflects the current thinking and practice among subject experts.
Vocabulary: set of terms and definitions to help harmonize the use of language in a particular sector, field or discipline.
Code of Practice: recommendations for accepted good practice; incorporates a degree of flexibility in application.
Classification: designations and descriptions of different grades of a product.