Why is my iPhone screen slowly dining itself?

Ok so the screen gradually but by bit got dimmer and dimmer and then stopped so now the screen is bright but not as bright as usual, why is this?

Low battery, and wasn't fully charged?

If you go to settings check the brightness level if your on auto brightness the turn it off. This adjusts the brightness of your phone to the bright of the room you are in

  • Why is my new iPhone 8 freezing the music on the lock screen and turning the volume up and down itself? When I'm listening to music and then click home to light up the screen to change a song or whatever the song will be almost over and it'll say it's at 0:30 seconds? And then when I go to Instagram it just turns the volume up and down without me pressing any volume buttons?
  • Why is my iphone charging extremely slowly? I have an iPhone 4S had it for about 3 years now and today it is charging extremely slow. It was on 90% and took almost an hour to get to 92%. This has happened before some months ago but I switched over the adapter and it was fine. This has not worked this time. Any suggestions as I can't afford a new phone right now
  • Why does my iphone screen keep controlling itself? So my iphone is in horrible shape, in terms of a broken screen. It's having a hard time responding to touch and I can't type. Also, it keeps opening apps on its own. Someone told me that the screen is pressing up against the digitizer and is acting as if I was touching the screen due to the cracks. If so, can I just replace the broken screen or do I have to buy another phone? I want to wait on the iphone 6 to use my upgrade.
  • Why did my iphone 4 screen turn on by itself? So my iphone screen just came on by itself, and has done it a few times. No notifications or anything just the lock screen lit up like a ghost… Why would this be? It's driving me crazy! I have the latest ios7 update, it is really freaking me out because it just turns on all by itself.