Each of the stairs / treads has a protective metal trim edging along the front, which is called step nosing and helps the carpet last longer, particularly in areas with high foot traffic.
Relevant image keywords:
architectural feature, architectural styles, architecture, architecture and buildings, balustrading, bannister, brown, building feature, built structure, design, domestic room, edging, furniture, handrail, hardwood, home interior, house, indoors, interior, living room, lounge, man made structure, no people, nosing, rail, railing, residential structure, room, skirting board, spindles, staircase, stairs, steps, steps and staircases, treads, trims, varnished, wood, wooden, wooden bannister, wooden handrail
