The most primitive (but still very common) method is all hand-hacking. You snapshot the project periodically by manually copying everything in it to a backup. You include history comments in source files. You make verbal or email arrangements with other developers to keep their hands off certain files while you hack them.

The hidden costs of this hand-hacking method are high, especially when (as frequently happens) it breaks down. The procedures take time and concentration; they're prone to error, and tend to get slipped under pressure or when the project is in trouble — that is, exactly when they are most needed.

As with most hand-hacking, this method does not scale well. It restricts the granularity of change tracking, and tends to lose metadata details such as the order of changes, who did them, and why. Reverting just a part of a large change can be tedious and time consuming, and often developers are forced to back up farther than they'd like after trying something that doesn't work.