Google Scholar is generally considered to be a search engine and not a database. However, the search engine is using information from a database. Google Scholar collected the full text of many publications with consent of the publishers. They use it to analyse the topics of the publications and to perform citation analysis. The public sees only a short description of the publication and when they want to read the full-text, they have to find a library that holds a license.
The other part of the database contains publications that are freely available on the internet and are found by Google's search robots. Google Scholar's search robots search websites where Google expects scholarly output: websites of research institutions, university repositories and 'open access' (=not licensed) scholarly journals.
It seems likely that Google Scholar offers more freely available content than other databases.Google Scholar is a very large database. Estimations are that GS contained about 160 million publications in 2014. GS is a multidisciplinary database. It contains publications about all disciplines.
Google Scholar presents the search results as short records. They contain just enough information to identify the publication. Sometimes there is a part of an abstract. There is no controlled vocabulary. Google does not use it. You don't know which words in the full-text are used for matching the publication with your search question. Often the only information that you have of the publication is the title. When you have to decide whether this publication is relevant or not, you have less information that with most other databases.
A GS record look like this. When you work on a computer within the network of the University of Groningen Library you will get a link to the licensed full-text, when available.
When Google Scholar does not know that you belong the the community of the University of Groningen, you have to install the library link facility first.
Cited by lists the publications that cited this publication.
Related articles finds documents similar to the given search result.
Besides access to the full text (when available) the record provides information about other publications that cite the publication. Google Scholar analyzes the reference lists in its content. When you click on CITED BY you see which publications cited it. There is also a link to RELATED ARTICLES; articles about a similar topic. Both links can lead you to other literature about your topic.
Google Scholar has another type of record. These are very elementary descriptions. You can recognize them as they begin with the word CITATION. This is what they are: Google found them in a reference list and did not see the full text. You can exclude them from your result set, if you don't want them.
The advanced search in Google Scholar has less options to limit your search than most other databases.Sort by date does not sort by date of publication, but by date that Google found the publication. You can click "Since Year" to show only recently published papers, sorted by relevance.
When you want to set Google Scholar to show which publications are available via the University of Groningen:
You will now be able to see, via the Get it! link, whether a document is available through the RUG.N.B. If you are working via the University network, these links are automatically selected.
Google Scholar has on online help that you find when you click About Google Scholar.Utrecht University Library published a libguide where they give a critical assessment of the pros and cons of Google Scholar as a search engine to find scholarly publications. This libguide is not part of the mandatory course.