までに

までに is a Japanese grammar expression used to indicate a specific point in time by which something should happen or be completed. It suggests that an action should occur before or by the stated time.

For example, if you say '明日までに宿題を終わらせます' (I will finish my homework by tomorrow), it indicates that finishing the homework is required to happen before the end of the day tomorrow.

Some nuanced points to consider:

• It can refer to both specific dates (e.g., '明日までに') and more general time frames (e.g., 'この夏までに').
• It is often used in both spoken and written Japanese, but is slightly more common in writing when expressing deadlines clearly.