The process of kanban, associated with the Toyota production system, incorporates the Japanese philosophy of Muda. Muda is the avoidance or elimination of waste and the removal of activities that are not useful or do not provide value to the customer (Baseer, Reddy, & Bindu, 2015; Stoica et al., 2016). The kanban process was developed by Taiichi Ohno to provide the Toyota production system with a practical approach in specific production and market conditions and to maintain a smooth production flow to promote the concept of continuous improvement (Ahmad, Dennehy, Conboy, & Oivo, 2018). Kanban is a Japanese expression meaning signboard (Tanner & Dauane, 2017) and was designed as a flow control system in manufacturing in which downstream process demand signals trigger upstream process activities (Abdullah & Qureshi, 2018). The kanban philosophy, although developed for the manufacturing sector to reduce waste in product production, has been applied to software development activities.
Kanban includes a visual workflow on a board divided into columns. Teams use a kanban board to visualize the progress of work to facilitate product improvements, monitoring of processes, and effective management of the workflow (Abdullah & Qureshi, 2018; Tanner & Dauane, 2017). The purpose of the kanban board is to improve the workflow by supporting the principles of limiting work in progress, creating value throughout the process, increasing throughput, and embedding quality within the process (dos Santos, Beltrão, de Souza, & Travassos, 2018; Lei, Ganjeizadeh, Jayachandran, & Ozcan, 2017). Additionally, kanban boards provide a process to manage the workflow, balance throughput, and make processes explicit as work moves through the different states (Ahmad et al., 2018). Each state in the kanban process has a clearly defined entry and exit point and provides the team and management with a visual representation of progress.
Work requests are defined in the kanban backlog to identify the work items the team needs to accomplish. In software development, stakeholders prioritize the requests regarding importance, urgency, or value (Tanner & Dauane, 2017). Features or requests are selected and placed on the board (Abdullah & Qureshi, 2018). Each column on the kanban board limits the amount of work in progress within the column or lane (Matharu, Mishra, Singh, & Upadhyay, 2015; Tanner & Dauane, 2017). Based on prioritization, work items are pulled through the workflow using defined stages such as “to do,” “in progress,” and “done.” Work items are tasks pulled only when required (Matharu et al., 2015). Each stage limits the number of items (work in progress) to avoid the potential for bottlenecks ( Abdullah & Qureshi, 2018; Dennehy & Conboy, 2017). Limiting work in progress restricts the number of ongoing activities to avoid an excess of initiated tasks and unfinished work (Matharu et al., 2015; Stoica et al., 2016). The Kanban method allows a team to respond to market changes, reduce waste, increase quality, and improve predictability.