Tier 1 US University means a top-level, highly ranked university considered the best at the national or global level in academics, research, faculty quality, and overall performance. These universities have high research funding and advanced facilities, and their reputation is quite strong, as is the case with Harvard, MIT, Stanford, Yale, etc. Getting admission in Tier 1 universities is tough as the competition is high, and generally, their degrees are recognised worldwide, which boosts your career.