Workers

A person is generally classed as a ‘worker’ if:

they have a contract or other arrangement to do work or services personally for a reward (your contract doesn’t have to be written)
their reward is for money or a benefit in kind, for example the promise of a contract or future work
they only have a limited right to send someone else to do the work (subcontract)
they have to turn up for work even if they don’t want to
their employer has to have work for them to do as long as the contract or arrangement lasts
they aren’t doing the work as part of their own limited company in an arrangement where the ‘employer’ is actually a customer or client

Employment rights
Workers are entitled to certain employment rights, including:

getting the National Minimum wage
protection against unlawful deductions from wages
the statutory minimum level of paid holiday
the statutory minimum length of rest breaks
to not work more than 48 hours on average per week or to opt out of this right if they choose
protection against unlawful discrimination
protection for ‘whistleblowing’ – reporting wrongdoing in the workplace
to not be treated less favourably if they work part-time

They may also be entitled to:

Agency workers have specific rights from the first day at work.