4.2 Use by others. Customers may allow their authorized users to use the Optimizely service, provided their use is only for the benefit of the customer and remains in accordance with this Agreement. The customer is responsible for the use and access of all authorized users and compliance with the terms of this Agreement. Aggregated use by all authorized users is taken into account within the applicable scope limits. There is no particular format that must be followed by a contract. In general, it will contain certain concepts, either explicit or implicit, that will form the basis of the agreement. These conditions may include contractual clauses or contractual guarantees. Of the 102 companies that marketed genetic testing for health purposes to consumers in 2014, 71 had commercial conditions available to the public: TIP: Contracts can be complex. It is important that you fully understand the terms of the contract before signing something.