writing
entry (e.g. to a form)
posting (e.g. to a blog)
ノートに書き込みをした。
I made notes in my notebook.
SNSへの書き込みに気をつけた。
I was careful about what I posted on social media.
教科書の書き込みが多くて読みにくい。
There are so many notes written in the textbook that it is hard to read.