Crowd computing: a survey
Crowd computing empowers computer systems by utilizing humans' perception, and their ability to solve non-algorithmic problems. In this approach, a group of humans are asked to contributively solve a problem that cannot be solved easily by individuals, or perfectly by computers. However, there are complexities in using humans to solve problems. Lack of generative models, complex cost models, lower speed in comparison to computers, limitation of knowledge and skills, noise, bias and error are examples of such complexities. An optimized crowd computing system should overcome these complexities, and improve the quality of solutions. 
This paper includes answers to three main questions: What is crowd computing? Why should one use crowd computing? And, how to use crowd computing? We will briefly answer the two former questions, while we will focus more on the latter one, specially on solving classification problems using multiple checking scenario. In addition, we will compare the current methods of crowed computing, and provide some guidelines for future works based on the current open issues in this field.