Full definition
Risk assessment is defined as: A risk assessment is a structured evaluation of the hazards a task or activity presents, with each risk rated before and after the controls the supplier will apply.
The standard UK format lists the hazard, who could be harmed, the likelihood and severity, the controls in place and the residual risk with those controls applied. It is signed and dated by a competent person.
Risk assessments are living documents. They should be reviewed whenever conditions change and always kept current for the site the work is being done on.