The umpires are appointed by the official body / association that organizes and manages a tournament or series. At the international level, the ICC appoints umpires for all international matches i.e. Test matches and one-day internationals.

The association in charge of cricket in a particular country does the same at the national level. For example, the BCCI appoints the umpires for all domestic matches. A regional association makes the appointments for all local-level tournaments. For example, the Mumbai Cricket Association appoints the umpires for the Kanga League.
 

In Test cricket, both the field umpires are from a 'neutral' country (not involved in the game), but the third (TV) and fourth umpires belong to the host country. If one of the field umpires is injured or falls ill, the third umpire takes over and the fourth umpire becomes the 'TV' umpire. The fourth umpire's primary job is to assist the field umpires by bringing replacement balls on the field in case a change is called for, and to assist the field umpires in supervising the rolling of the pitch and discussions if any with the captains or players.

In bilateral and triangular limited-overs tournaments, one field umpire belongs to the host nation and the other is neutral, coming from a country not involved in the competition. In tournaments featuring four or more nations, the field umpires and the third umpire are 'neutral'. There have been umpteen instances of a field umpire being replaced for part or the entire duration of the match. Once Dickie Bird collapsed in Sharjah due to excessive heat and had to be replaced by a local umpire who stood at the square-leg position at both ends. David Shepherd, the other field umpire, officiated from the bowling ends for the remainder of the game.

There was a queer incident in the Georgetown Test of the 1964-65 series between West Indies and Australia. One of the umpires was from Guyana, but the local umpires' association wanted both the officials to be Guyanese. The West Indies Cricket Board refused to oblige, and the association protested by forcing the Guyanese umpire to step down on the eve of the game. Gerry Gomez, former West Indian Test cricketer and the Chairman of the Selection Committee, was asked to supervise the proceedings until a replacement arrived from another island. He agreed, as did the Australians, and went on to do a fine job on the first two days. In fact, he stood for the entire duration of the game even though a replacement arrived!

The umpires are the final judges as far as the condition of the ground, weather and light (suitability for play) are concerned. However, if they are not in agreement over something, like the time at which to resume play after an interruption, they may ask the captains what they feel. In fact, even if both umpires feel that the conditions are not good enough, they still have the option of asking the captains whether they want to go out there. If both skippers agree, play could start / resume. 
 

England were 17-3 on the opening day of the Jamaica Test in the 1997-98 series against the West Indies. The pitch was uneven and dangerous, and three English batsmen had been hit by nasty deliveries. The umpires decided to abandon the game after consultations with rival captains Mike Atherton and Brian Lara. A few months before this game, a one-dayer at Indore between India and Sri Lanka was abandoned in similar circumstances when Sri Lanka were 17-1 in the first innings.

Only the batsmen at the crease can appeal for bad light. After an interruption, the umpires may offer the batting side the option of resuming, even if they themselves feel that the light hasn't improved.

Australian maestro Stan McCabe was going great guns in a Test match against South Africa in 1934-35. The light was poor, but he wanted to continue as he was well set. The South African captain complained to the umpires about the light and stated that he was concerned about the safety of his players. But the umpires rightly turned down his request to halt play, as only the batsmen can complain about the light. In other situations, the umpires can 'offer the light' (the option of going off) to the batsmen.

In the 1930s, Lord Tennyson was batting in a county match in poor light. When his partner got out, the Lord appealed against the light, but the umpires were unmoved. When the new batsman arrived at the crease, Lord Tennyson told him to be careful. The batsman replied, "My Lord, I can hear you, but I can't see you!". The umpires called off play a little later!

The umpires change ends after the first innings of each side in a two-innings match. In a rain-affected game between India and Glamorgan at Cardiff in 1946, the tourists were on the verge of enforcing the follow-on on the third and final day. To prevent the loss of more time, Indian skipper Vijay Merchant asked his counterpart if Glamorgan could start its second innings without returning to the pavilion. The latter agreed.

So Glamorgan's last pair became their opening pair in the second innings. The ball was unchanged and the Indian bowler who had ended Glamorgan's first innings opened the bowling in the second innings. The spectators were initially confused, but they understood what had happened when they realized that the umpires had changed ends.

- By Piloo Reporter