Org provides two types of timers. There is a relative timer that counts up, which can be useful when taking notes during, for example, a meeting or a video viewing. There is also a countdown timer.
The relative and countdown are started with separate commands.
Start or reset the relative timer. By default, the timer is set to 0. When called with a C-u prefix, prompt the user for a starting offset. If there is a timer string at point, this is taken as the default, providing a convenient way to restart taking notes after a break in the process. When called with a double prefix argument C-u C-u, change all timer strings in the active region by a certain amount. This can be used to fix timer strings if the timer was not started at exactly the right moment.
Start a countdown timer. The user is prompted for a duration.
org-timer-default-timer sets the default countdown value. Giving
a numeric prefix argument overrides this default value. This command is
available as ; in agenda buffers.
Once started, relative and countdown timers are controlled with the same commands.
Insert the value of the current relative or countdown timer into the buffer. If no timer is running, the relative timer will be started. When called with a prefix argument, the relative timer is restarted.
Insert a description list item with the value of the current relative or countdown timer. With a prefix argument, first reset the relative timer to 0.
Once the timer list is started, you can also use M-RET to insert new timer items.
Pause the timer, or continue it if it is already paused.
Stop the timer. After this, you can only start a new timer, not continue the old one. This command also removes the timer from the mode line.