The answer by Amon is quite correct. But I want to mention a few other GDPR requirements.
When a Data Controller (DC) first acquires Personal Data (PD) about a Data Subject (DS), the DC must send the DS a notice containing various information. This is required by GDPR Article 13 if the data was acquired directly from the DS, and by GDPR Article 14 if the PD is obtained from some other source.
An Article 13 notice must include:
- 1(a) the identity and the contact details of the controller and, where applicable, of the controller’s representative;
- 1(b)the contact details of the data protection officer, where applicable;
- 1(c) the purposes of the processing for which the personal data are intended as well as the legal basis for the processing;
- 1(d) where the processing is based on point (f) of Article 6(1), the legitimate interests pursued by the controller or by a third party;
- 1(e) the recipients or categories of recipients of the personal data, if any;
- 1(f) where applicable, the fact that the controller intends to transfer personal data to a third country or international organisation and the existence or absence of an adequacy decision by the Commission, or in the case of transfers referred to in Article 46 or 47, or the second subparagraph of Article 49(1), reference to the appropriate or suitable safeguards and the means by which to obtain a copy of them or where they have been made available.
- 2(a) the period for which the personal data will be stored, or if that is not possible, the criteria used to determine that period;
- 2(b) the existence of the right to request from the controller access to and rectification or erasure of personal data or restriction of processing concerning the data subject or to object to processing as well as the right to data portability;
- 2(c) where the processing is based on point (a) of Article 6(1) or point (a) of Article 9(2), the existence of the right to withdraw consent at any time, without affecting the lawfulness of processing based on consent before its withdrawal;
- 2(d) the right to lodge a complaint with a supervisory authority;
- 2(e) whether the provision of personal data is a statutory or contractual requirement, or a requirement necessary to enter into a contract, as well as whether the data subject is obliged to provide the personal data and of the possible consequences of failure to provide such data;
- 2(f) the existence of automated decision-making, including profiling, referred to in Article 22(1) and (4) and, at least in those cases, meaningful information about the logic involved, as well as the significance and the envisaged consequences of such processing for the data subject.
An article 14 notice is similar, but some of the information to be included is different. It must include:
- 1(a) The identity and the contact details of the controller and, where applicable, of the controller’s representative;
- 1(b) the contact details of the data protection officer, where applicable;
- 1(c) the purposes of the processing for which the personal data are intended as well as the legal basis for the processing;
- 1(d) the categories of personal data concerned;
- 1(e) the recipients or categories of recipients of the personal data, if any;
- 1(f) where applicable, that the controller intends to transfer personal data to a recipient in a third country or international organisation and the existence or absence of an adequacy decision by the Commission, or in the case of transfers referred to in Article 46 or 47, or the second subparagraph of Article 49(1), reference to the appropriate or suitable safeguards and the means to obtain a copy of them or where they have been made available.
- 2(a) the period for which the personal data will be stored, or if that is not possible, the criteria used to determine that period;
- 2(b) where the processing is based on point (f) of Article 6(1), the legitimate interests pursued by the controller or by a third party;
- 2(c) the existence of the right to request from the controller access to and rectification or erasure of personal data or restriction of processing concerning the data subject and to object to processing as well as the right to data portability;
- 2(d) where processing is based on point (a) of Article 6(1) or point (a) of Article 9(2), the existence of the right to withdraw consent at any time, without affecting the lawfulness of processing based on consent before its withdrawal;
- 2(e) the right to lodge a complaint with a supervisory authority;
- 2(f) from which source the personal data originate, and if applicable, whether it came from publicly accessible sources;
- 2(g) the existence of automated decision-making, including profiling, referred to in Article 22(1) and (4) and, at least in those cases, meaningful information about the logic involved, as well as the significance and the envisaged consequences of such processing for the data subject.
Under either article 13 or 14, if the purposes(s) of processing change, an updated notice must be sent.
Each article lists exceptions, circumstances in which the notice may be omitted.
I believe that the notice requirement is more often overlooked or not complied with than the lawful basis requirement.