Below are the instances when we have to use "ser"

 

	with an adjective to express a permanent or inherent quality
	El azúcar es dulce	sugar is sweet
	mi padre es calvo	my father is bald
	mis hermanas son altas	my sisters are tall

 

	for occupations and nationality
	Son italianos	they are Italian
	Pablo es español	Pablo is Spanish
	Es profesor	She is a teacher

 

	with nouns or pronouns
	es un coche	it is a car
	son niñas	they are girls
	somos nosotros	it's us
	¿Eres John?	Are you John?

 

	with possessions
	es mio	it is mine
	son de Pedro	they are Pedro's
	este es mi libro	this is my book

 

	with time, dates and numbers
	son las seis	it is 6 o'clock
	dos y tres son cinco	two and three are five
	Es el 21 de diciembre	it is 21st December
	la temperatura es de 20 grados	it is 20 degrees

 

	with events
	when there is an event or an occasion such as a party we use "ser" even though we may seem to be indicating position which is usually with "estar"
	La fiesta es en casa de Susana	The party is in Susana's house

 

	with passive constructions
	Although it is not as common as in English there is a Spanish equivalent of the English passive.
	fue construido en 1800	it was built in 1800
	el cuadro fue robado	The picture was stolen

 

	when speaking about what something is made of
	esos zapatos son de plástico	those shoes are (made of) plastic
	es de oro	it's made of gold

 

	with "how much / many?"
	¿cuánto es?	How much is it? (asking about the price)
	¿cuántos son?	How many are there?