at

In Filipino, at is a neutral conjunction used in all levels of speech. Its primary role is to link grammatically equivalent elements.

1. Basic Usage
It is most commonly used to join nouns, adjectives, or verbs. While some formal writing avoids starting a sentence with at, it is very common in natural speech, literature, and narrative prose to show continuity between thoughts.
Example: maliit at mataba (small and fat).

2. The Enclitic Form (-'t)
When the preceding word ends in a vowel (a, e, i, o, u), at frequently contracts to -'t. The apostrophe and the letter t attach directly to the end of the preceding word, not the following word. This also occurs with specific grammatical words, adverbs, and conjunctions ending in the letter n, where the n is dropped and replaced by the contraction (this does not apply to regular nouns). This creates a smoother flow in speech.
Example: babae at lalaki → babae't lalaki; bagaman at → bagama't.

3. Expressing 'That' (Complementizer)
A unique function of at is connecting an emotion or a greeting to a following clause. This is common with salamat (thank you) or mabuti (it is good).
Example: Salamat at tinulungan mo ako. (Thank you for helping me. / Lit: Thank you that you helped me.)

4. Joining Clauses
It can connect two complete thoughts. In this context, it sometimes implies a sequence of events, similar to 'and then'.
Example: Kumain siya at natulog. (He ate and [then] slept.)

5. Expressing Reason or Cause
In conversational Filipino, at is frequently used to introduce a reason or cause, similar to 'because', 'since', or 'as'. It often connects a command or statement to the reason behind it.
Example: Bilisan mo at aalis na tayo. (Hurry up because we are leaving soon.)

6. Fixed Expressions
You will see at embedded in numbers (e.g., dalawampu't isa for 21) and in formal conjunctions like subalit (but) or sapagkat (because). While these formal conjunctions originated as contractions and are now spelled as single words without apostrophes, numbers retain the apostrophe and are written as separate words.

7. Spoken Reduction
In rapid, casual speech, at is often reduced to a quick 't' sound or blended entirely into the surrounding words, which is important to note for listening comprehension.

8. Alternatives to 'At'
To avoid overusing at, remember that Filipino has other words for addition. Use pati when you mean 'including' or 'as well as', and saka (moreover / and also) when adding supplementary information.