Attestation is a legal acknowledgement of the authenticity of a document and a verification that proper processes were followed. It is an act of witnessing the signing it to verify that it was properly signed by those bound by its contents. In simple words, an attestation is a third party recognition of a documented agreement's validity.
Meeting of minds or mutual assent expressed or implied by both the parties to the contract.
As per the Secretarial Standards issued by Institute of Company Secretaries of India, harbour seal means, the metallic seal of a corporation which may be affixed only with the approval of the Board of Directors of the corporate.