Will updating my iPhone 3GS delete everything on it

I have an iPhone 3GS and I want to update it to the latest iOS so I can download the newer apps. When I try to download on it says it will delete all of my apps and media on my iPhone. Some people say it will restore it back after the update but why doesn't it say it anywhere on the message that pops up? Anyway I'm one click away from updating… Will it delete all my stuff?

No it shouldn't do just back it up before!

I have updated and have not seen that message just one that says it will reset phone after but I have done 2 updates and nothing was removed from my phone

Try a backup first the go update.

No. Under normal circumstances with a properly synced iPhone updating the firmware will not lose any contacts. All information including contacts, calendars, apps and music are stored in iPhone backups or your iTunes library and are not affected by iOS firmware updates.

Restoring your iPhone as a new device will wipe all settings, but the contacts can still be restored from your iTunes backup. In the event that contacts are lost on your iPhone, this means that something is seriously wrong either with your iPhone or computer.iTunes will not delete contacts when updating your mobile device to the latest operating system.

Do iOS update with iTunes it will recommend you first to backup your data, if you will have any problems with update you can restore your information at any time, it's safe and comfortable.