Avoid drawing temporary construction lines

When you need to draw a line that doesn’t start on a geometric point (endpoint, midpoint, etc.) of another object, you might draw a temporary line, called a construction line, from an existing object to the desired start point of the new line.
Then you would draw the new line. Then erase the construction line.
This is so very 70′s, left over from hand drafting days! Instead you can use other drafting tools to start your new line more quickly and avoid the erasing process. (How many of you have forgotten to erase that line?)

The From object snap

From isn’t really an object snap, but it lets you start lines a certain x,y offset from an existing point. Use it when you know the x and y distances from some point.
Let’s say that you have a rectangle, the outer edge of a window frame, and you want to draw the glass pane as another rectangle inside the first one. You might draw a line 3,2 units from the lower-left corner so that you have an endpoint from which to start your inside pane.
Instead, here’s what you should do:
1. Draw the first rectangle.
2. Start the RECTANG command for the second rectangle.
3. At the RECTANG prompt, type from and press Enter. (There are other ways to get to it, but typing it is the fastest.)
4. At the Base point: prompt, use an OSNAP to specify the lower-left corner of the first rectangle.
5. At the <Offset>: prompt, enter the offset, such as @3,2. Your rectangle starts in the right place.
IMPORTANT: You must put the @ before the offset, even if you’re using the default relative coordinates.