There are many different kinds of wire, here some useful infos for wire related to making circuits.
Types of Wire
flexible and good for all connections that need movement
but you need to take care that the wire is reinforced / "strain-relieved" at the solder joint so that it will not break
Solid Core / Hook-up Wire
stiff and good when you want to bend wire and for it to stay in shape (like when making protoboard circuits!)