TCAS (Thai University Central Admission System) is the system used for applying to universities in Thailand. It organizes all university applications into different rounds, such as Portfolio, Quota, Admission, and Direct. Each round has its own rules, score requirements, and deadlines.

TCAS helps students choose the right round for their abilities and plan how to prepare for exams like TGAT and A-Level. It is the main system every student uses when applying to university in Thailand.