In one form I can stretch to infinity, in another I have a clearly defined limit.
In one form I am very flexible, in another I am exceedingly rigid.
In one form intersections are catastrophic, in another intersections are common and can be helpful.
In one form I am a physical object, in another I am a conceptual object
In both forms I am used daily by millions of people all round the world.
What Am I?
Don't forget the spoiler tags.
If you get the correct answer, you must then think of a thing whose first letter begins with the end letter of the answer to this problem. So if the answer was apple, you need to think of an object that starts with 'e' and post a riddle about that. We can keep going until people get bored. However it does rely on getting the answer to this right first. If you really can't be bothered to think up a new riddle, say so in your answer. First person who comments something like 'I'll do it' can have the honor.
No hate, this is my first entirely made up word based riddle. Have Fun!