If you click and hold the selection button there will be options
Select
You can click and drag with this one
Select Box
Make a box to select
Hotkeyb
Middle mouse button exclude what is inside it.
Select Circle
Paint and select what was hit
Click and hold the left mouse button and scroll the middle mouse wheel to increase or decrese the radius
Hotkeyc
Temporarily puts in select circle mode
Hold Shift + left mouse click to deselect object
Select Lasso
Make a lasso to select.
Ctrl + Right click mouse button to add to selection
Ctrl + Shift + Right click mouse button to remove from selection
Click in empty space to deselect all.
To add objects to the selection, hold the shift key.
Shift key toggles selection.
When multiple objects are selected, the last object selected is yellow selected. The others are orange.
The yellow object is the active object.
Only one object can be active at a time.
To change the active object, hold the shift key and click the object you want to be the active object.
Some commands take into account what is the active object.
To remove an object from selection, it first have to be an active object. Shift key and right mouse button click on the object you want to deselect. If it wasn't the active object, it will become the active object. If you press shift key right click button again on the selected object, it will no longer be selected.