A time period or time frame was a specific or predetermined segment of time, on any given timeline, when or where something existed.
It was observed by Data, in 2369, that whenever they interacted with the temporal fragments they encountered, they became integrated into that fragment's specific time frame. Data and Geordi La Forge were later able to isolate themselves from the effects of the other anomalous time frames they encountered by wearing an altered phase discriminator. (TNG: "Timescape")
In 2370, Captain Jean-Luc Picard shifted through three different time periods, the anti-time future, anti-time present, and anti-time past. With regards to Picard's time shifts, and the past unfolding differently than he remembered, Data suggested that "it would appear there is a discontinuity between the time periods you described. Events in one time period would seem to have no effect on the other two." (TNG: "All Good Things...")
In 2372, Julian Bashir had a penthouse apartment in a Julian Bashir, Secret Agent holoprogram. The penthouse's decor was appropriate for the 1964 period in which the holoprogram took place. (DS9: "Our Man Bashir")