The verb "ser" means "to be", and it describes essential qualities that are unlikely to change, such as name, nationality, religion, physical appearance, or moral characteristics:

- Yo soy Marcos. (I am Marcos).
- Ella es Juana. (She is Juana).
- Nosotros somos españoles. (We are Spaniards.)
- Mustafá es musulmán. (Mustafá is muslim.)
- María es alta y guapa. (María is tall and good looking.)
- Javier es honesto. (Javier is (an) honest (person).)
- Juan es de Sevilla. (Juan is from Seville.)
- Katarina es alemana. (Katarina is German.)

  "Ser" is also used to link one element with another in a sentence. If the second element is a noun, "ser" identifies it with the subject (profession, occupation). If the second element is an adjective, then "ser" serves to describe a characteristic of the subject. And, if the second element is a verb, we use "ser" with the preposition "para" to indicate purpose:

- Ella es profesora. (She is a teacher.)
- José es abogado. (José is a lawyer.)
- Don Juan carlos es el rey de España. (Juan Carlos is the king of Spain.)
- Este coche es muy veloz. (This car is very fast.)
- Este vestido es muy bonito. (This dress is very pretty.)
- Este libro es para estudiar. (This book is to study.)
- Este martillo es para clavar clavos. (This hammer is to nail nails.)

  Note that in Spanish we omit the indefinite article when stating a profession or occupation. We only use the indefinite article (un, una, unos, unas) when we qualify the noun:

- José es un buen abogado. (José is a good lawyer.)
- Alan García es un mal presidente. (Alan García is a bad president.)

  "Ser" is also used to describe what something is made out of (color and material):

- Este anillo es de oro. (This ring is (made of) gold.)
- Esta corbata es de seda. (This tie is (made of) silk.)
- Esta mesa es negra. (This table is black.)

   "Ser" is also used to express possession or origin:

- Esto es mio. (This is mine.)
- Este coche no es tuyo. (This car is not yours.)
- Esta camisa es de Italia. (This shirt is from Italy.)

   "Ser" is also used to refer to the time, the seasons, and days of the week:

- Hoy es Viernes Santo. (Today is Good Friday.)
- Es verano. (It is summer.)
- Es temprano. (It is early.)
- Son las dos y media. (It is half past two.)
- Es la una en punto de la tarde. (It's one o'clock in the afternoon.)
- Hoy es primero de enero. (Today is the first of January.)

   As an auxiliary verb, "ser" forms the passive voice:

- El ladrón fue detenido anoche. (The thief was arrested last night.)
- El presidente fue electo el año pasado. (The president was elected last year.)

  Finally, "ser" is used with certain impersonal expressions:

- ¡Es tarde! (It is late!)
- ¡Es muy urgente! (It is very urgent!)