Ser and estar are two forms of 'to be' in Spanish, each used based on permanence or temporariness of the characteristic. 'Ser' for permanence, 'estar' for temporary states.
Ser and estar are two different forms of the verb 'to be' in Spanish. 'Ser' is used for more permanent characteristics or essence, while 'estar' is used for temporary states or conditions.
For example, 'Yo soy católica.' indicates a more permanent characteristic ('I am Catholic'), while 'Yo estoy cansada.' indicates a temporary state ('I am tired').