What is a Tick

From Guide

A tick occurs once every hour in which the world advances: Resources are gained, squads move, units are trained, battles take place and your score updates. The symbol for a tick is .

For example: building a specific structure may take 4 ticks, meaning 4 hours. You place your order to build the structure and after 4 hours it will be ready. Sending a squad takes ticks too: depending on how far your destination is, the squad travel time will increase. A classic example would be sending your squads to attack a target 12 ticks away – you submit your order and return to check the battle results the day after (although there is a limit of 24 ticks when it comes to squads).

Ticks advance regardless if you're logged on or not. To play the game you're advised to login at least once a day to check your colony's status.