Timeseal

In an internet game, a move takes time to travel from the player to the server. This network delay is called latency or lag. Without a special mechanism, the server may subtract it from the clock as though the player were still thinking.

On FICS, the Free Internet Chess Server, Timeseal is a program or feature on the player's device that acts as a relay and records when information is transmitted. The server can use those records to distinguish approximate thinking time from transmission time and avoid charging the latter to the player.

Timeseal does not remove lag, speed up the connection, or guarantee immediate screen updates. Its purpose is fairer clock accounting when communication is delayed. Historically, it could be built into a FICS interface or run as a separate program before login.

It is also not a time-control mode. An increment adds a fixed amount after each move, while a delay postpones clock deduction according to the game's rules. Timeseal tries to compensate for a technical network delay rather than grant extra time by rule.