How can massless particles (even when at rest) combine together to form objects that have mass?

Question

I was reading this- https://en.wikipedia.org/wiki/Matter and in the first paragraph I got across the line stating - "... massless particles may be composed to form objects that have mass (even when at rest)."

From another Wikipedia article I got to knew that there are only two massless particles viz. photon and gluon. So, how is this feasible that many photons/gluons can be compsoed to form object that have mass? Is it through the pair production from the energy that photon carries or is it something else? Can pair production like thing happen with gluons too?

Comments

This is nonsense. Massless particles cannot be at rest. Wikipedia is not always reliable, as you can see from this manifestly wrong claim. For other wrong claims see my article 
''Misconceptions about Virtual Particles''   

---

Oh my Gosh! PO becomes almost like Physics SE -- total laymen are here!

---

vote to close as not being graduate+ level

---

You need to upvote the linked vote to close, not the comment!

---

@ArnoldNeumaier Probably my reputation is too low or I just not cool enough, but I can't vote there -- all I can see is "This question has been hidden".

---

@AndreyFeldman:  It has been closed in the mean time. As long as there are not enough close votes, one can upvote. (You have enough reputation to vote.)

---

Sorry, no, it is not yet hidden, and one needs 500 rep to upvote a close vote.

---

@AndreyFeldman you are highly cool ;-) !

The issue is that to see the closevote thread you need 500 rep, which in particular at quiet times sometimes gives us a hard time to gather the 3 closevotes needed to close a question

---

@Dilaton OK, then I will work harder on answering questions to get enough reputation.

---

@AndreyFeldman ok it is closed for now ...