might; perhaps; indicates possibility
Expresses that something might be true or might happen, equivalent to 'might' or 'perhaps'.
かもしれない is used when you are not sure about something but think it is possible. It is softer than saying 'I know' and can also express a slight worry or uncertainty. For example, if you hear a noise, you might say '誰か来たかもしれない' (Someone might have come). It is a common way to guess or speculate.
The pattern is quite flexible and can be used in both speech and writing. In casual conversation, you will often hear it shortened to 'かも' (since the full form is a bit long), but 'かもしれない' itself is still natural in everyday talk. It is not as formal as 'かもしれない' in written essays, but it is acceptable in most situations.
One thing to remember: do not use the polite form of the verb before it. You cannot say '行きますかもしれない'. Instead, use the plain form: '行くかもしれない'. This is a common mistake for learners.