Canon EOS Rebel T6i EF-S 18-55mm IS STM Lens Kit Instruction Manual - Page 209

Using AF to Focus (AF Method) 3 Focus on the subject.  Aim the AF point over the subject and press the shutter button halfway.  When focus is achieved, the AF point will turn green and the beeper will sound.  If focus is not achieved, the area frame will turn orange. 4 Take the picture.  Check the focus and exposure, then press the shutter button completely to take the picture (p.192).  If the camera does not focus on the desired target subject with automatic AF point selection, select a zone or switch the AF method to [FlexiZone - Single] and refocus.  The number of AF points varies, depending on the [A3: Aspect ratio] setting. At [3:2], [4:3], and [16:9], there are 49 AF points. At [1:1], 35 AF points. 209