Guess the object - What Am I Riddle (Part 1)

Question

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!}

Answer 1

Network. The virtual/social vs road networks.

In one form I can stretch to infinity, in another I have a clearly defined limit.

The virtual/social can cross boundaries reaching the endless depths of connections between people. Roads are physically bounded.

In one form I am very flexible, in another I am exceedingly rigid.

The digital can be instantly modified and twisted (eg. changing physical layout of a network but regaining functionality, or people changing locations not interfering with their friendship). Roads are very difficult to change.

In one form intersections are catastrophic, in another intersections are common and can be helpful.

Car accidents vs. meeting people / transferring data

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.

self explanatory

Answer 2

The answer I had in mind was a plane which is both a physical object (airplane) and a mathematical concept.
- Geometric plane can stretch infinitely along a 2D surface, Aeroplane has a defined shape
- Aeroplane is quite flexible (at least the wings certainly are), Geometric plane, is not flexible at all, because it lays along a 2D surface, as soon as it bends, it is no longer a plane.
- When two aeroplanes intersect...... pretty obvious, Geometric plane intersection, can give us solutions to mathematical problems.
- Aeroplane - Physical, Geometric - Conceptual
- Both are used around the world.