In policy debate, the flow is the name given to a specialized form of notetaking, which enables debaters to keep track of all of the arguments in the round.
It incorporates specialized abbreviations and notations to allow debaters to keep up with the rapid speed of delivery inherent in most speeches. As in V for value and C for criterion.
Flowing can be done on paper or on a laptop using a spreadsheet program such as Microsoft Excel. In collegiate debate, computers may be used in any round, however in high school this is sometimes not allowed. Those tournaments that follow the National Forensics League regulations may or may not allow laptops depending on the district, but many so-called national circuit tournaments and some states allow the use of laptops in round. Debaters often prefer to use legal paper to be able to capture the numerous arguments read on each position. Numerous sheets of paper (or tabs in a spreadsheet) are used each round as debaters normally use one sheet for each different type of argument read.
After the 1NC and 2AC, the second negative speaker and the first affirmative speaker will "backflow" their partner who has just given a speech. This can often be accomplished during the cross-examination or the prep time preceding the next speech. The 1NC requires backflowing because they need to flow what issues they are going to argue ('take') in the 1NR and the 2AC needs backflowing because they need a flow of these arguments so that they can carry the argument to the end of the round ('extend') during the 2AR.
The 1AC is not backflowed because most affirmative debaters are presumably already familiar with the arguments or they have flowed the arguments before or during the speech. The negative block is not backflowed because the 1NR is prepping during the 2NC and the 1NR has no further speeches. The rest of the rebuttals are not backflowed for the same reason.
Shadowflowing is a technique commonly used to prepare for 1AR's, widely considered to be the toughest speech. It consists of flowing the 1AR answers to the negative arguments, rather than the negative arguments themselves.