Overview
The toga was not simply what Romans wore; it was what Roman citizens were entitled to wear. Foreigners and exiles could not, and the garment therefore functioned as a legal document you put on in the morning — which is why its varieties are so carefully distinguished in the sources.
Key garments and style
Under the toga went a wool tunic, belted. The toga itself was undyed wool, and its versions did the signalling: the plain toga virilis of the adult male citizen; the toga praetexta with its purple border, worn by magistrates and by freeborn boys until they came of age; the toga pulla, dark, for mourning; and the toga candida, whitened with chalk by men seeking office, from which the word candidate descends.
A married woman of standing wore the stola, a long slip over a tunic, with the palla as a mantle outdoors, and woollen fillets in her hair — an outfit that likewise announced legal status rather than taste.
The Republic legislated against display repeatedly. The lex Oppia of 215 BC, passed in wartime, limited the gold a woman could own and the coloured clothing she could wear; its repeal twenty years later, after women demonstrated in the streets of Rome, is one of the few recorded public protests about clothing in the ancient world.
Transition
Under the Empire the toga grew larger and more unwieldy until it was ceremonial only, and the tunic and the imported silks the Republic had legislated against became ordinary.