A hackstreak is a consecutive string of days in which you have performed at least one hack. Hacking at any time of the day (local time) can count for the hackstreak for that day. For example, if the first hack of your streak occurs at 11:59 pm Monday local time, performing another hack a minute later will fall on Tuesday, and therefore count as the second day of your streak. Drone hacks do not count toward a streak.
When you hack any portal for the first time that day, a toast message will appear showing your hackstreak status. That hack will also earn a 500 AP bonus and double hack yield. This yield multiplier stacks with increases from using an apex or fracker, or glyph hacking. Your hackstreak is complete when you reach the seventh day; that hack will earn a 1000 AP bonus and triple hack yield. It will also increase the hackstreak cycle statistic on your profile by one. Completing a certain number of hackstreak cycles will earn the Epoch medal. Hackstreak cycles do not have to be consecutive to count toward the medal; after you complete a seven-day streak, you can skip one or more days before starting the next streak without resetting progress on the medal.