Ser ser frequently refers to a permanent condition.
Estar estar often refers to a temporary condition

In English, the verb "to be" can be used to tell
how something is  the condition temporary está
what something is   the essence permanent es
How is the apple? ¿Cómo está la manzana?
It is unripe. Está verde ( no está madura) temporary
What color is the apple? ¿De qué color es la manzana?
It is green. Es verde permanent
ser is highly irregular. Following is its conjugation

yo  él, ella, usted nosotros/as vosotro/as ellos,ellas,ustedes
Present soy eres es somos sois son
I am you are he/she is, you are we are you are they, you are
Past fui fuiste fue fuimos fuisteis fueron
 preterite I was you were he/she was, you were we were you were they, you were
Past era eras era éramos erais eran
 imperfect I was you were he/she was, you were we were you were they,you were
Future seré serás será seremos seréis serán
I will be you will be he/she/you will be we will be you will be they, you will be

Ser is used to express: 
Here are the main uses of ser: 
To tell the time, the hour, day, and date  
Es la una. It is 1:00 o´clock. This is the only time (1:00) where the Spanish language use  ES
Son las dos.  It is 2:00 o´clock.
Son las tres. It is 3:00 o´clock.
Hoy es viernes.  Today is Friday
Es sábado 15 de Junio.  It is Saturday, June 15th.
To indicate origin, nature or identity 
Soy de Argentina.  I am from Argentina.
El perfume es frances. The perfum is french
No soy marinero, soy capitán. I am not a mariner, I am a captain.
Ella es maestra. She is a teacher
Juan es médico.  Juan is a doctor
Ellos son actores.   They are actors.
Soy Argentina.  I am Argentinian.
Ellos son europeos.  They are European.
Tú eres americana? Are you American?
Religious or political affiliation
El es católico.  He is Catholic.
Ellos son musulmanes.  They are Muslims.
The material something is made of
El anillo es de oro. The ring is gold.
La bandeja es de plata. The tray was silver.
Los zapatos son de cuero. The shoes are leather.
La mesa es de roble. The table is oak.
To indicate possession or ownership 
El libro es mío.  The book is mine.
Aquella es mi casa. That is my house.
 Relationship of one person to another
Ellas son hermanas.  They are sisters.
Nosotras somos amigas.  We are friends.
Eric es nuestro jefe. Eric is our boss.
 Certain impersonal expressions.
Este mensaje es importante. This message is important.
El exámen fue difícil.  The test was difficult.
 To indicate where an event takes place 
El concierto es en la playa.  The concert is on the beach.
La fiesta será en mi   casa.                                        The party will be at my house.
 Essential qualities. With adjectives to indicate inherent, innate or essential  characteristics 
La casa es grande. The house is big.
Soy feliz. I am happy by nature.
Las golondrinas son negras. The swallows are black.
Estas son las monedas de mi collección.  These are the coins of my collection.
To indicate existence 
Ser o no ser.  To be or not to be.

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