este/esta/estes/estas

In Portuguese, demonstrative adjectives like este are used to identify specific objects based on their location relative to the speaker.

1. Spatial Use (Near the Speaker):
Use these words for objects you are holding or that are within your reach. It is often paired with the word aqui (here).

• Este livro (This book - near me)
• Esta caneta (This pen - near me)

2. Agreement and Neutral Form:
These words must change to match the noun in gender and number (este, esta, estes, estas). For unspecified things, concepts, or objects whose name you don't know, use the neutral invariable pronoun isto.

3. Temporal Use (Current Time):
We use these to refer to the current time period, such as este ano (this year) or esta semana (this week).

4. Discourse and Textual Use:

• Cataphoric: Use 'este' to introduce new information that is about to be stated (e.g., 'A minha ideia é esta: ...').
• The Latter: In formal writing, when two things are mentioned, 'este' refers to the most recent one (the latter), while aquele refers to the first one mentioned (the former).

5. Contractions and Exceptions:
Usually, these form mandatory contractions with prepositions, such as neste (em + este) or deste (de + este). Note that the preposition a does not contract with these forms (e.g., 'a este'). In formal writing, they also remain separate if the demonstrative is the subject of an infinitive verb (e.g., 'a chance de este plano dar certo').

6. Regional Note:
In casual Brazilian Portuguese, speakers often use esse/essa even for things near them. However, in formal writing and in European Portuguese, the distinction is strictly maintained.