Is the labour union term related to its definition of a crusty formation over a wound? We unpack the history.
Here are some ways writers and actors want the public to support them during the strikes.
Cabinet minister alleged strikers are "absolutely intent on causing the maximum disruption to hardworking people".
The RMT boss said: "If we fight together we are an unstoppable force in this society!"
Expect travel disruption on Thursday, Friday and Saturday.
The Labour leader is under pressure over his stance on the party's approach to striking workers.
Passengers have been urged to only travel by train if "absolutely necessary".
"The nature of work does need to be reappraised."
RMT accuses transport secretary of "inflaming tensions" over walkout set for next week.
Boris Johnson went to see the custodians at the front door of No.10 to personally apologise for what had happened.