Observe the P-T phase diagrams for a given substance A. Then melting point of A(s), boiling point of A(l), critical point  of A and triple point of A (at their respective pressure) are respectively -

mp T3→ solid & liquid,bpT4→liquid-gas Critical point T2,Critical Temperature Temperature above which gas can't be liquefied even high pressure is appliedtriple point (Temperature at which all the three phases co-exists ) T1→solid liquid gas