Salesforce Object Search Language: What is SOSL and when to use SOSL?

When to Use SOSL?
Use SOSL when you don’t know which object or field the data resides in, and you want to:
Retrieve data for a specific term that you know exists within a field. Because SOSL can tokenize multiple terms within a field and build a search index from this, SOSL searches are faster and can return more relevant results.
Retrieve multiple objects and fields efficiently where the objects might or might not be related to one another.
Retrieve data for a particular division in an organization using the divisions feature.
Retrieve data that’s in Chinese, Japanese, Korean, or Thai. Morphological tokenization for CJKT terms helps ensure accurate results.