Click on the Select text icon on the toolbar, then drag the mouse to select the desired objects. When right-clicking on the mouse (Mac: Ctrl + Click), a menu will appear giving you the choice to copy the text to the clipboard; highlight, underline, cross out, squiggly underline, or replace the selected text; or insert new text after the selection.
For rectangular text selection, hold down Ctrl (Command for OSX) while dragging the mouse. The cursor will change to to indicate that a different selection mode is active.
To exit the selection mode, simply click on the hand tool or Esc on the keyboard.