Number of Players
Each team has up to 15 players on the field, 8 forwards and 7 backs. They also have up to 8 substitutes (of varying propotions of forwards and backs) on the bench.
Starting players are numbered 1 through 15 based on their position. The number is not specific to a player like some sports. The forwards are numbered 1 to 8, the backs 9 to 15. The substitutes are 16 through 23 and usually correspond to specific positions.
Forwards
The forwards in a team are generally larger than the backs and will usually be more involved in tackling, rucks, and mauls. They are also the people who participate in scrums and lineouts.
Backs
Backs are generally smaller and faster than the forwards. They are usually the ones who score tries and kick conversions and penalties.
Positions
1. Loosehead Prop
The Loosehead Prop is on the left side of the scrum, with their head on the outside of the scrum. They are also common lifters in the .
2. Hooker
The main roles of the Hooker are to throw the ball into the lineout, and to “hook” the ball backwards in the Scrum.
3. Tighthead Prop
The Tighthead Prop is on the other side of the scrum, with their head on the inside of the scrum (between the opposition Hooker and Loosehead Prop). They are also common lifters in the lineout.
The two Props, along with the Hooker, are known as the front row.
4 and 5. Lock
The two Locks are usually the two tallest players in the team. They are the main jumpers in the lineout (since the goal is to gain height).
Most top international Locks are over 2 metres tall (or about 6 feet 10 inches).
The front row along with the two Locks are known as the tight five.
6. Blindside Flanker
The Blindside Flanker is on the side of the scrum with the smallest distance to the touchline. They are generally more regarded for their strong tackling ability.
The blind side is the one closest to the touchline.
7. Openside Flanker
The Openside Flanker is on the side of the scrum with more room to play, or the opposite side to the Blindside.
Some countries, particularly South Africa, swap the numbers 6 and 7. 7 will be Blindside and 6 Openside.
8. Number 8
The Number 8 is at the back of the scrum. They are commonly lifted in a lineout and are a good balance of mobility, power, and height.
The 6, 7 and 8 combine to form the back row. The above 8 are the forwards.
9. Scrumhalf
The Scrumhalf is usually the smallest player on the field and is the main distributor of the ball. They are the player who puts the ball into the scrum, and are usually the first to the ruck to secure the ball.
10. Flyhalf
The Flyhalf is the main playmaker of the team. They are usually the best kicker and will often decide whether to kick or run, effectively running the offence.
11. Left Wing
The Left Wing runs fast. Occasionally they will kick. They also finish off team movements by scoring tries.
12. Inside Centre
Often a second playmaker (along with the Flyhalf), they are a strong runner, a useful kicker and have the speed to break the line.
13. Outside Centre
More defensive-minded, the Outside Centre can be responsible for organising the defence.
14. Right Wing
Like the Left Wing, the Right Wing is fast, can kick, and scores tries.
15. Fullback
The Fullback is the last line of defence and often catches kicks from the other team. They are usually good kickers. Sometimes they will also join the attack, e.g. by receiving a pass from the Outside Centre, running it, and passing it to a winger.
Substitutes
There is no requirements for the composition of the substitutes other than a reserve Hooker and Props. But below is a common bench.
16. Reserve Hooker
Replaces the Hooker.
17 and 18. Reserve Props
Replaces the Props.
Sometimes Props and Hookers can play both positions, but mostly they will only play one.
19. Reserve Lock
Replaces a Lock. Sometimes can also replace a back row player.
20. Reserve Backrow
Replaces someone in the backrow (No. 6, No. 7, or No. 8).
21. Reserve Scrumhalf
Replaces the Scrumhalf. Occasionally will be put elsewhere in the backline due to injury.
22 and 23. Reserve Back
Usually more backline players. Sometimes more forwards if it is predicted to be a forward-oriented match.
Variations and Key Terms
Fewer than 15 players on the field
A team can have fewer people in the field primarily if a player (or players) on their team have recieved a red or yellow card.
Larger benches
Occasionally, in less important matches (particularly Barbarians matches), the benches may be larger. This can lead to less exhaustion as players are rotated more frequently. Sometimes, they will employ interchange benches, where players can sub on and off.
Bench splits
The positions listed above in the substitutes are simply common reserve players. The bench above would be a 5-3 split. However, teams can occasionally favour a more heavy forward-oriented bench, with 6 forwards and 2 backs (a 6-2 split). On rare occasions, when there may be heavy forward attrition, a team may go with a 7-1 split.