godan verb (-mu), transitive verb
Used for writing information into a designated space on a form, document, or field.
申込書に必要事項を書き込んでください。
Please fill in the required information on the application form.
解答
I write the answer in the answer column.
godan verb (-mu), transitive verb
post a message; write a comment
Common for posting messages, comments, or entries on online bulletin boards, forums, or social media.
掲示板に質問を書き込んだ。
I posted a question on the bulletin board.
ブログにコメントを書き込む。
I write a comment on the blog.
godan verb (-mu), transitive verb
Computing sense: writing data to a storage medium or memory. 'Flash' refers to writing firmware or data to flash memory.
USBメモリにファイルを書き込む。
I write a file to the USB memory.
新しいファームウェアをROMに書き込む。
I flash the new firmware to the ROM.