Functional illiteracy consists of reading and writing skills that are inadequate "to manage daily living and employment tasks that require reading skills beyond a basic level". Those who read and write only in a language other than the predominant language of their environs may also be considered functionally illiterate in the predominant language. Functional illiteracy is contrasted with illiteracy in the strict sense, meaning the inability to read or write complete, correctly spelled sentences in any language. The opposite of functional illiteracy is functional literacy, literacy levels that are adequate for everyday purposes, and adequate reading comprehension, the ability to read collections of words (such as sentences and documents) and comprehend most or all of their meaning.
The characteristics of functional illiteracy vary from one culture to another, as some cultures require more advanced reading and writing skills than do others. In languages with phonemic spelling, functional illiteracy might be defined simply as reading too slowly for practical use, an inability to effectively use dictionaries and written manuals, and other factors. Sociological research has demonstrated that countries with lower levels of functional illiteracy among their adult populations tend to be those with the highest levels of scientific literacy among the lower stratum of young people nearing the end of their formal academic studies. This correspondence suggests that the capacity of schools to ensure students attain the functional literacy required to comprehend the basic texts and documents associated with competent citizenship contributes to a society's level of civic literacy.