Have you ever had an issue with Stranded Wire not cooperating and having a strand that sticks out when you try and insert it into a connection point?
Wire Ferrules are a Good connector to help with that.
These can be crimped onto the wire to make a good connection point.
They can be used on a single wire or have two wires tied together.
A couple examples would be to use them on the end of a wire to plug into Terminal Block going onto a DIN Rail.
Another easy option it to put it on the end of Speaker Cable to plug into Speaker Connectors.
The Different styles are:
DIN - Deutche Industrie Norman - German, This is the most common one used
W - Weidmuller - European Code
T - French - Telemechanique
The Ferrules come in a few options