How to use tags?

All tags, especially Basic tags, provide an easy and flexible way to group tasks. With tags:

On Today page, you can easily retrieve all tasks having the same tag using the Tags filter,
On Reports page, besides generating reports on tasks, you can also generate bar or pie chart based on tags.

Using Advanced tags, one can store numeric or other information on tasks. These information will later be summarised based on the type of tags.

Examples:

Numeric/Sum tag: If you want to log how long distance you run during your daily jogging sessions, you can first create a Numeric tag with a subtype Sum, using km as the unit and 5 as the default number. After you assign this tag to Jogging task, when you log jogging, besides the time is recorded, a default distance of 5 km is also stored with the task entry. You can then adjust the 5 km to reflect the actual distance.
Later on, you can pull up the sum of jogging distance for a day, past week or month in Reports.
Numeric/Hourly tag: If you want to log your consulting hours, you could use a Hourly tag, by defining a default hourly rate, and a currency code, eg $., After assigning this tag to consulting tasks, every time when consulting task is logged, a fee calculated by duration of the task entry and the hourly rate is also logged.
Drop down Tags: For instance, you track working time through a task. But you are working with several clients and you want to know how much time you spend for each client individually. You can then use a Drop down tag Clients, in which you define clients as alternatives. So when every time you log a task entry, you also mark one client. In Report page, you can then retrieve statistics of working hours aggregated for each client.

Not only you can assign one tag to several tasks, you can also assign several tags to one task.

Examples:

You track several exercise forms. You can assign all of them an Exercise tag. You can then assign a Cardio tag on those belong to cardio types and a Strength tag on those belonging to strength types. That way you can retrieve statistics not only on all exercises as one group, but also on Cardio and Strength separately.
At the same time as you track you fees earned on your consulting tasks using a Numeric/Hourly tag, you can also use a Drop down tag to assign priorities to each task.