Tier 1 ,Tier 2 ,Tier 3 companies

Companies which usually have a revenue more than 1 billion $ comes under tier 1 companies with more than 50000 employees.
Companies with revenue over 100 million comes under tier 2 companies list wioth employment of 4000 t0 10000 employees approx.
Comapnies having revenue less than tier 2 companies are classified as tier 3.

1 Million = 10 Lakhs
1 Billion = 1000 Millions