To know when to use ser and estar, we need to learn what each one means:

Key Uses:

• Ser: We use this word for things that stay the same. This includes traits like personality, where someone is from, and who they are.
  • Example: Ella es alta. (She is tall.)
• Estar: We use this word for feelings, locations, and actions happening right now.
  • Example: Ella está feliz. (She is happy.)

How to Change the Verbs

Present Tense:

• Ser: soy, eres, es, somos, sois, son
• Estar: estoy, estás, está, estamos, estáis, están

Past Tense:

• For completed actions (Preterite):

  • Ser: fui, fuiste, fue, fuimos, fuisteis, fueron
  • Estar: estuve, estuviste, estuvo, estuvimos, estuvisteis, estuvieron

• For ongoing actions in the past (Imperfect):

  • Ser: era, eras, era, éramos, erais, eran
  • Estar: estaba, estabas, estaba, estábamos, estabais, estaban

Future Tense:

• You can create a future form by adding to the basic verb form:
  • Example: Ser: seré (I will be), Estar: estaré (I will be)

Reflexive Verbs:

• These verbs show actions you do to yourself. For example, levantarse means "to get up."

Agreement:

• Adjectives must match the nouns in gender (male or female) and number (singular or plural).
  • Example: El chico alto (The tall boy), Las chicas altas (The tall girls).

Subjunctive Mood:

• This mood is used to express hopes or wishes.
  • Example: Espero que ella esté contenta. (I hope that she is happy.)

Demonstrative and Possessive Adjectives:

• Demonstrative: este (this), esa (that)
• Possessive: mi (my), tu (your), su (his/her)

How to Build Sentences:

• The basic structure is Subject-Verb-Object:
  • Example: Yo como manzanas. (I eat apples.)

Basic Conjunctions:

• Some common conjunctions are: y (and), o (or), pero (but)
  • Example: Yo quiero pizza y tú quieres ensalada. (I want pizza and you want salad.)