Generally, primary sources are considered as documents or footage that was created during the time of an event. If no primary sources are available, other sources can be considered primary for this purpose.
There are three types of sources that can obtain information: primary, secondary and tertiary. The type of source used can indicate as to whether the information is true and factual and if the sources are an expert on the subject. Tertiary sources are hardly ever used since they have the least reputable source and would generally be hearsay as one friend speaks to another. An example of this would be friend John talking to friend Sam about what was heard in the news today, and Sam takes that information as truth and tells others. This can lead to unintentional misinformation.
A primary source is an account of something that happened by someone involved in the event, or someone directly affected by the event. Creative literature, depending on the author and time period the work was produced, can be considered primary. Some examples can include the diary of Anne Frank, articles from a time period under investigation and a country's constitution or state documents.
A secondary source would be something that information from primary sources was collected for analyzing and collection of data. This can include, but is not limited to, term papers written using primary sources, magazines where writers review other findings and textbooks written years after the original subjects.