The "Break" command is one of the most difficult to understand for new AutoCAD users. It is used to erase a portion of a line arc or circle, or it can be used to make an endpoint within a line or arc, in effect breaking it at a point.
The command BREAK can be typed in at the keyboard. It also exists on the Toolbar, in the Pull-down menu (under "Modify"), and on the on-screen menu (under EDIT). I have found that the pull-down menu Break is the most useful, because there are several variations of the command function which are included on that menu but not on the others.
The basic sequence of using this command for erasing a portion of a line, arc, or circle is as follows (I will use the typed command method here, but using the Toolbar or on-screen menus are identical in sequence):
2. Pick the line, arc, or circle that you want to erase a section of. Note that you can only select one object.
3. Type F <RET> [this will allow you to specify the location of the first "Break Point"]
4. Select (OSNAP if desired) the location of the first break point on the line, arc or circle.
5. Select (OSNAP if desired) the location of the second break point on the line, arc or circle.
6. The line will be broken and a gap will appear between the two break points.
2. Pick the line, arc, or circle that you want to erase a section of. Note that you can only select one object.
3. Type F <RET> [this will allow you to specify the location of the first "Break Point"]
4. Select (OSNAP if desired) the location of the first break point on the line, arc or circle.
5. Type @ <RET> [this means "at the same point as the first point]
6. The line will be broken at the first break point you selected. Note that you cannot really "see" that the line or arc is "broken" but in reality there will be two separate segments of the line or arc that can be independently moved or changed in layer, linetype, color, elevation, or thickness. Also, you cannot break a circle at a point.