| Name | Description | Type |
| User | the person or organization that is involved in a crowdsourcing activity | concept |
| Requester | the initiator of a crowdsourcing project (any individual, company, or public organization) | concept |
| Participant | the person that submits a contribution | concept |
| Project | a carefully planned crowdsourcing activity that includes one or more tasks | concept |
| Task | the smallest indivisible unit of work that is clearly described by a single instruction | concept |
| Target Audience | an initial general restriction of the size of the crowd (internal, external, both) | concept |
| Action Type | the type of action that is required to solve a crowdsourcing task | concept |
| Aggregation Type | the mechanism of how the contributions of the crowd are combined | concept |
| Latency Type | the time when the solution of a crowdsourcing task can be expected (immediate, untimed) | concept |
| External Resource | all additional inputs that are required to accomplish a crowdsourcing task (e.g., applications, documents, or datasets) | concept |
| Contribution | all data records, content items, documents, or code fragments that are part of the solution of a crowdsourcing task | concept |
| Requirement | any human or technical aspect that is required to solve a crowdsourcing task | concept |
| Human Requirement | any aspect that supports the composition of the crowd (demographic characteristics, qualification, etc.) | concept |
| Technical Requirement | any aspect that specifies the required system of a crowd member | concept |
| Reward Mechanism | the configuration of a certain type of a reward mechanism | concept |
| Reward Nature | the definition of how a worker’s contribution is rewarded (fixed, performance-based, proportional, voluntary) | concept |
| Reward Type | the specification of what kind of reward is offered (coupon, discount, good, lottery, money, no reward, resource access, virtual points) | concept |
| Payout Method | the specification of which participants are rewarded (all, the winner only, or the top ten participants) | concept |
| Evaluation Mechanism | the configuration that contains aspects of how a crowdsourcing user or contribution is evaluated | concept |
| Evaluation Time | the point of time when the participants or the contributions are evaluated (after, before, simultaneously) | concept |
| Evaluation Source | the agent that is engaged in the evaluation process (requester, participant, third party organization, algorithm) | concept |
| Evaluation Method | the method that is used for the evaluation (majority decision, control group) | concept |
| Evaluation Specificity | the specificity of the evaluation (an acceptance or rejection, a rating, an assessment form, or a free text response) | concept |
| Evaluation Subject | the subject of the evaluation (contribution, participant) | concept |
| title | a short phrase to describe the instance | attribute |
| description | one or more sentences to describe the instance | attribute |
| goal | the desired result of a crowdsourcing activity | attribute |
| category | the class of a crowdsourcing activity (e.g., idea generation, problem-solving, or content creation) | attribute |
| instruction | a direction that lead the crowd towards a common goal | attribute |
| submission time | the time when the task is accessible for the crowd | attribute |
| closure time | the time when the task expires | attribute |
| confidentiality level | a value that limits the access to certain types of information | attribute |
| complexity level | the amount of skills, experiences, and knowledge that is required to solve a crowdsourcing task | attribute |
| priority level | the importance of a crowdsourcing task compared to other concurrent tasks | |
| visibility mode | a specification of whether the workers can or can not see each other’s contributions | attribute |
| interaction mode | the configuration that enables or disables peer-to-peer collaboration | attribute |
| estimated duration | the estimated time required to complete a crowdsourcing task | attribute |
| number of assignments | the number of participants who will be assigned to one crowdsourcing task | attribute |
| amount | the number of points or the monetary value of the reward | attribute |
| currency | the currency of the monetary reward | attribute |
| gender | the gender that a participant should have | attribute |
| minimum age (minAge) | the minimum age that a participant should have | attribute |
| maximum age (maxAge) | the maximum age that a participant should have | attribute |
| language | the language that a participant should speak | attribute |
| country | the country in which a participant should live | attribute |
| job title | the job title that a participant should have | attribute |
| qualification type | the academic degree, certificate, or skill that is required to solve a crowdsourcing task | attribute |
| qualification level | the proficiency level that is required for a certain qualification | attribute |
| approval rate | the ratio of properly solved tasks to the number of submitted tasks | attribute |
| number of approved tasks | the number of properly solved tasks | attribute |
| hardware device | any hardware device (e.g., personal computer, mobile phone, smartphone, tablet computer) | attribute |
| hardware feature | any build-in feature of the hardware device (e.g., processor, memory, GPS, camera, accelerometer, gyrometer) | attribute |
| operating system | any operating system for personal computers or mobile devices (e.g., Microsoft Windows, OS X, Linux, Android, Windows Phone, iOS) | attribute |
| software platform | any operating system independent platform (e.g., Java, Firefox) | attribute |
| issues (requester, project) | the project that a requester issues | relation |
| submits (participant, contribution) | the contribution that a participant submits | relation |
| includes (project, task) | the crowdsourcing tasks that are included in a project | relation |
| has next (task, task) | the subsequent crowdsourcing task | relation |
| has previous (task, task) | the preliminary crowdsourcing task | relation |
| owns (task, contribution) | the contributions that belong to a crowdsourcing task | relation |
| belongs to (contribution, task) | the task that is associated to a contribution | relation |