Source clips, clip instances, subclips, and duplicate clips

In Premiere Pro, a clip points to a source file. Trimming a clip, or editing it in any way, does not affect the source file. For example, if you import a 30-minute file into Premiere Pro, you create a 30-minute clip that points to that source file. If you trim the clip to a five-minute duration, the 30-minute source file remains on your hard disk, but the clip refers only to a five-minute section of it. Premiere Pro stores information about clips in clip metadata fields in project files, but stores information about source files in XMP metadata fields.

You can trim source clips, clip instances, subclips, or duplicate clips. You can trim all types of clips in sequences in much the same way. The clip types differ in the following ways:
Source (master) clip
The clip originally imported into the Project panel. It is listed in the Project panel only once by default. If you delete a source clip from the Project panel, all of its instances are also deleted.

Clip instance
A dependent reference to a source clip, used in a sequence. Each time you add a clip to a sequence, you create another instance of the clip. A clip instance uses the name and source file reference used by its source clip. While clip instances are not listed in the Project panel, they are differentiated in the Source Monitor menu if you open instances there. The Source Monitor menu lists instances by name, sequence name, and In point.

Subclip
A section of a master clip that references the master clip’s media file. Use subclips to reference discreet sections of long master clips. (See Creating subclips.)

Duplicate clip
An independent copy of a source clip, which you create manually using the Edit > Duplicate command. You can also create a duplicate clip by importing the same file more than once. Unlike a clip instance, a duplicate clip maintains its own reference to the original clip’s source file on disk and exists as an additional clip in the Project panel. Premiere Pro does not delete a duplicate clip when you delete its original from the Project panel. Master and duplicate clips can be renamed independently.