Why is my phone sporadically having lines, like static, running through the screen?

Howdy elaine!,

It sounds like your phone is exhibiting some graphical anomalies intermittently. Normally that would indicate to me that you have a hardware issue, but I would like to make sure all the bases are covered and troubleshoot the software first before coming to that conclusion. Start by quitting all the running apps:

Force an app to close in iOS
https://support.apple.com/en-us/HT201330

1. Press the Home button two times quickly. You'll see small previews of your recently used apps.
2. Swipe left to find the app you want to close.
3. Swipe up on the app's preview to close it.

When you have done that force your device to restart with the Home and the Sleep/Wake buttons, and test the issue again:

iOS: Turning off and on (restarting) and resetting
http://support.apple.com/en-us/HT201559

If the issue persists, backup your device to iTunes, then restore it as new and verify that it works.

How to erase your iOS device and then set it up as a new device or restore it from backups
https://support.apple.com/en-us/HT204686

If it does, then restore your backup to either verify it still works and the software just needed reinstalled, or isolate the issue to the backup file itself.

If nothing works then you will need a repair on your phone:

https://www.apple.com/support/iphone/repair/other/

Thank you for using Apple Support Communities.