तो

The particle ‘तो’ has two main usages in Hindi:

1. A conjunction meaning ‘so’
2. An emphatic particle

At the beginning of a sentence, तो is used an an introductory conjunction, like “so” in English:

तो आप क्या किया आज – “So, what did you do today?”

If तो immediately succeeds a word, it emphasizes the previous word. More specifically, it contrasts the previous word or phrase with some other part of the same context. This usage is very subtle.

खाना अच्छा तो है, पर बहुत महंगा है – “The food is good, but it is very expensive”. In this example, तो contrasts “good” with “expensive”.

खाना तो अच्छा है, पर चाय अच्छा नहीं है – “The food is good, but the tea isn’t” . In this example, तो contrasts “food” with “tea” – one is good, the other is not.

Often the contrast is not explicit, and can be somewhat vague:

आज तो काम कर रहा है – “Today he is working” (but yesterday?)

वह कल दफ्तर में तो थी – “She was in the office yesterday” (but today she is somewhere else?)

Often तो can have the sense of “at least” as in:

ये तो बता दो – “At least tell me this”