# A Comprehensive Survey on the Societal Aspects of Smart Cities
## 3 Smart Cities' Technologies
### The Power of \"Open Data\"  
Data are the lifeblood of a smart city, and their free flow is essential for a smart city's goals. In this section we will discuss open data and why a smart city having open data sources is an asset and the challenges and opportunities of open data.  
However, what is open data? A widely accepted definition is the one from Open Definition: \"Open data and content can be freely used, modified, and shared by anyone for any purpose\" [214]. The full open definition [215] provides a detailed explanation of the meaning of this summary and the standards that data must meet to be considered open. This definition is crucial as open data are essential for interoperability, enabling disparate entities, which may have never had contact with each other, to access, use, and combine their datasets [216].  
It is important to note that open data does not always equate to open access. Data collection can be an expensive process, and the collected data can hold significant value. Therefore, the institution responsible for the collection may want to recoup costs. This can be one of the biggest challenges in implementing open data, with private companies charging high prices for their data, making it inaccessible to those without the resources to pay for it. However, it is possible to pay for data while still keeping it open, and this can actually improve the quality of the data, as long as the cost of the data does not impact the access to it [217]. It is also important to note that many institutions collect data as a necessity for their work, and making it open data and sharing it free of cost is, at worst, a minor burden.  
The cities' authorities are significant sources of data, and while some data should not be shared due to privacy and confidentiality concerns (e.g., personal citizen data or confidential information), there is plenty of data that can be made available to the public. Open data has significant benefits for a government, including socially, economically, and efficiency improvements [218]. By making that data freely accessible, it is possible to gain even more benefits, as private entities can create systems that make use of that data to improve the smart city environment in novel or more efficient ways.  
Open data are also available from various sources, including scientific, public authorities, non-governmental organizations (NGO), non-profit organizations (NPO), and social media. Often, these raw data need preparation before distribution. This involves sanitizing the data to remove personal information, duplicates, and errors, as well as conforming to open standards. Afterwards, the final dataset should then be made accessible to the public.  
Distributing datasets can be a challenging task, particularly for non-influential organizations. It is crucial to advertise the datasets effectively to ensure maximum exposure. With the vast amount of data available on the Internet today, datasets can easily become lost in the noise. As such, efforts have been made to create repositories that allow for datasets to be collected in one place, grouped by relevance, and be easily searchable. These repositories are certified, ensuring that the data contained within is trustworthy. Some well-known repositories include FAIRSharing, the Registry of Research Data Repositories (Re3 Data), Zenodo, and Network Data Exchange (NDEx), but more are available for different types of data [219].