The Remembrance is an epic poem, a heroic saga of sorts. It is a form of written tradition that The Clans keep. Each Clan has its own version of the poem, describing the events from the beginnings of Exodus to the present, from the perspective of each Clan.
The Remembrance is one of the few non-technical books that the Clan society specifically values. Everyone can recite passages from it, the printed versions are well-illustrated (similiar to old copies of the Bible in our time), and scenes from the poem are often found painted, even on the sides of BattleMechs and battle armor.
Being included to The Remembrance is one of the highest honors a member of Clan can get.
An example passage, commemorating Vladimir Ward:
From a 'Mech grave he rose, snarling
Ready to do battle for his vanquished Clan
Stalking the Falcon Khans, who would remake us
His actions, the Wolf incarnate.
- The Remembrance (Clan Wolf), Passage 412, Verse 10, Lines 9-12
Sources: The Clan term glossary found in various BattleTech source books; Excerpt from BattleTech Field Manual: Crusader Clans, ISBN 1-55560-323-2, FASA 1998