primary source
A primary source is firsthand evidence — a trace left directly by the time a historian is studying, whether made by someone who was there or simply produced in that period. A soldier's letter home, a wedding photo, a peace treaty, a clay pot, a diary entry: these are the raw material of history, the closest we can get to touching the past directly. Think of it as a witness who left something behind, rather than a storyteller summing things up afterward.
This matters because everything we claim to know about the past has to rest on traces like these. A historian is a bit like a detective: the primary sources are the fingerprints and footprints at the scene, and the job is to read them carefully, weigh them, and piece together what most likely happened.
One common mix-up: "primary" does not mean "true" or "unbiased." A wartime poster, a politician's speech, a one-sided diary — all are primary sources precisely because they come from the period, and all can be slanted, mistaken, or self-serving. The skill is not blind trust but careful interrogation: who made this, when, for whom, and why?
Anne Frank's diary is a primary source; a biography of her written decades later is a secondary one.
"Primary" here means "first in order" (from Latin primus), closest to the event — not "most important." Its companion is the secondary source, a later account written by someone interpreting those firsthand traces.