But there are a few requirements that the thrower needs to comply with.
Both feet must be outside the field of play and the ball must reach the 5m line before it touches the ground, or is played at by a player, so it cannot be rolled back into play.
If the mark for the lineout is outside the 22m line and the thrower takes it back inside that line before throwing it, and is then it is subsequently kicked out on the full again, it is deemed to have taken it backwards and the added ground is lost.
In this case, the new lineout would be opposite where he kicked it, not where the ball went out.
Interestingly, a player taking a quick throw-in does not have to throw the ball in straight – it just must not go forward towards the opponents' goal line.
The ball must be thrown in straight at a conventional lineout.
Just how straight is often a matter of conjecture and is often loudly disputed by opposition players and one-eyed spectators.
In the not-too-distant past, "straight" meant the ball had to alight more or less on the mark of touch – a direct line running from the touchline and at a right angle from the mark made by the linesman
These days, "straight" means the ball has to alight anywhere inside the inside shoulder of the player catching or deflecting it.
So, effectively ,straight means anywhere between the inside shoulders of the two lines of players in the lineout.
Before the lineout begins, this space should be a one metre gap, so effectively the thrower has a one metre target to reach.
The reality is, of course, he can throw the ball slightly on his side of the mark of touch, as long as it alights inside the inside shoulder of the player who catches or deflects it.
Therefore, today's thrower has a one metre channel in which to land the ball instead of the old straight line, and players and spectators should realise that works for both teams.
The team throwing in the ball determines the maximum number of players each side can put into the lineout.
If the thrower's team put five into their lineout, the opponents cannot have six or more.
It doesn't happen very often, but it they want, the throwing team can put more than the usual seven players, but the non-throwing team can have less numbers than their opponents if they choose.
The opponent of the player throwing the ball into the lineout, usually the opposing hooker, must stand two metres on his side of the mark and two metres in from touch, which usually is not a problem for referees.
But what can be an issue is where the receiver stands.
To comply with law, both receivers must also stand two metres back from their players in the lineout, but they can be anywhere between the 5m and 15m lines.
What you often see is these players standing a good 5m back from the lineout for whatever reason.
Another issue to watch for is players, usually the last player in the lineout, moving infield beyond the 15m line before the lineout ends.
This gives them an unfair defensive advantage, as they are then out among the opposing backs when they are not entitled to be.
The lineout can end in one of five ways before the players not in the lineout can advance from behind their 10m offside lines.
The ball can leave the lineout, by being passed or knocked back, or go beyond the 15m line, or back inside the 5m line.
A ruck or maul can form, but all the feet of players in the ruck or maul must move beyond the mark of touch – a referee usually holds his hands up to stop the backs from advancing until players in the ruck or maul reach that point.
Or the ball can become unplayable, which again does not happen very often.
