What it was
The Senate was the council of Rome’s leading men, the most enduring institution of the Roman state, traditionally dating back to the kings and lasting through Republic and Empire.
Role
Under the Republic it was the dominant organ of government, guiding finance, foreign policy, and administration through its prestige and the magistrates drawn from its ranks, though formal power lay with the assemblies and elected officials. Under the emperors it lost real power, largely ratifying the emperor’s will while keeping honor and administrative duties.
Fate
It continued in reduced form to the end of the Western Empire. Its emblem SPQR (the Senate and People of Rome) remained the symbol of the Roman state, and the word senate endures for legislative bodies worldwide.