Time
Time as an exact concept is fairly recent. In period most people would have been content knowing what month it was and in a lot of cases they wouldn't have minded only knowing which season it was currently - after all the church would tell them which holy days were approaching.
Time during the day was regulated in many places by the church - bells rang at the times of significant services, and people might agree to meet "after Vespers" or similar. Events might occur "between Terce and None". The church had a difficult job to calculate just when the bells should be rung. Initially complex calculations might be performed from the rising of stars, and then using astrolabes. The church might be able to afford a water clock or marked time candles, and while these made life much easier for monks, these made little difference to the layman - he just listened for the bells (approximately 6 times a day).
By the late 13th century, with spreading urbanism, the use of public sundials became more widespread and significant - knowing the time of day more precisely made regulating buisness easier. Following on from this need, mechanical clocks were adopted from the astronomy community to city use. Because such mechanical clocks were adopted from the astronomy community, unlike the earlier mentioned sundials which marked the "canonical hours", these were marked into 24 equal hours, thus beginning England and France's transition to modern hourly divisions.
The first useful pocket watches only started to appear just as the 16th century was drawing to a close.
The introduction of mechanical clocks actually caused much discontent among workers. Previously, they had worked during the daylight hours - when clocks became available, their masters required them to work the same amount of time the year round. Consequently, they had to work more hours, often after the sun had gone down. In some cases, riots ensued.
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