MySQL Backups - Innodb

[Purna Chinta]

Hi,

I am new to MySQL. I have read on mysqldev, that using --single-transaction, a consistent backup can be made and all read/write operations will not be blocked. But how mysqldump see's the page as consistent if a write is operation is going on??? Also, by the time dump moves on, I might have completed 'n' number of data changes, but they will not get reflected on dump...will each page record any transaction number on it???? By the time the backup reaches the page, it might have overwritten 'n' times by another transactions...will it still treat the dump as consistent one???

Please help with clarification.