Hi Sarah, 

If the time zone remains the same for everyone, the values within date/time fields will remain constant for all Users on the records. 

Here is how the Date/Time fields work in Salesforce

Date/Time fields are stored internally in UTC which aligns with Greenwich Mean Time (GMT)

If your user's time zone is not GMT, but for example GMT+1, an extra hour will be added when viewing the data via the UI in Salesforce.

For example: 

If the Date/Time field in the CSV file is: 
2016-03-01T08:00:00.000Z  (Z stands for UTC time)

Then the Date/Time field in the Salesforce UI will be: 
01/03/2016 09:00

Salesforce just added +1 hour to the time field, because the user's time zone is GMT+1.

When the Daylight Savings Time (DST / "summer time") applies, it adjusts the time based on the viewing users Time Zone settings, + 1 hour in most cases. 

In this case, if the user's time zone GMT+1 (as an example) the following applies:

If the Date/Time field in the CSV file is: 
2016-08-20T08:00:00.000Z  (Z stands for UTC time)

Then the Date/Time field in the Salesforce UI will be:
20/08/2016 10:00

You will see, that Salesforce adds +2 hours:
+1 hour because the user's time zone is GMT+1
+1 hour because of the DST: it adds +1 hour to the winter time.

These examples presented with the GMT+1 time zone, but the rule applies to any time zone, and the +1 hour DST for any location, where DST applies.

Let me know if this helps

Anudeep