Q: Will iTunes' "Back Up Now" command delete/replace any old backups when creating a new backup?

Will iTunes' (version 12.3.1.23) "Back Up Now" command delete/replace an old backups when creating a new backup?
In other words, will older backups be deleted / replaced automatically when I back up my iPhone 5s using iTunes (version 12.3.1.23) "Back Up Now" command?

I don't want to accidentally delete a backup or cause it become unreadable or unusable... So how do I avoid accidentally deleting a backup or causing it to become unreadable or unusable?

Notes on how I might use backups:

• I might need to restore from a backup should something go badly wrong on my iPhone.
• I recently purchased and began using the program iExplorer to access and export information contained within my iPhone backups, information such as messages, voicemails, and notes.

Here's my question expressed in the context of a scenario:

Given the following fundamental events took place, would I permanently lose data and information (such as anything deleted in event #3) from iPhone Backup #1 by creating iPhone Backup #2?

1. At the beginning of 2015, I begin using a new iPhone.
   
   
2. At the end of 2015, I make an iTunes backup (iPhone Backup #1) of my iPhone 5s, following the steps outlined here for a mac How to back up your devices using iCloud or iTunes - Apple Support.
   I believe this creates a usable/accessible copy of the data stored on my phone at the time of this backup.
   So iPhone Backup #1 will contain the majority* of the content I've kept from 2015.
   For example, within the backup are copies of all my messages (or notes, voicemails, contacts...just fill in the blank) that I've kept from 2015.
   
   
3. I delete data from my iPhone to free up storage space.
   For example, I delete all the text messages that I've kept from 2015 off my phone.
   
   
4. At the end of 2016, I make a second iTunes backup (iPhone Backup #2) of my phone, following the same steps I used to make iPhone Backup #1.
   Similar to iPhone Backup #1, I believe iPhone Backup # 2 would be another usable/accessible copy of the data stored on my phone at the time when its created. However a year has now passed since iPhone Backup #1, and the data stored on my phone has now changed (notably, see event #3)...
     (iPhone Backup #2 = iPhone Backup #1 - any deleted content + any new content)
   So iPhone Backup #2 will contain the majority of the content I've kept from 2016 plus anything I kept from 2015.
   For example, within this backup are copies of all my messages (or notes, voicemails, contacts...just fill in the blank) that I've kept from 2016, but no messages for 2015.
   
   

*I know iTunes backups don't contain a copy of all content from a device according to About backups in iCloud and iTunes - Apple Support, but these backups are still fairly comprehensive.

SPECS:

• iPhone 5s
  16 GB 
  iOS 8.1.3

• iTunes (version 12.3.1.23)

• MacBook Air (13-inch, Late 2010)
  OS X  El Capitan version 10.11.1 (15B42)
  Processor: 1.86 GHz Intel Core 2 Duo
  Memory: 4 GB 1067 MHz DDR3
  Physical Drive: APPLE SSD TS128C Media
  Capacity: 120.47 GB (120,473,067,520 bytes)

I've been reading and referencing these articles as well as some of the built in iTunes help articles and am trying to practically understand the content:

1. About backups in iCloud and iTunes - Apple Support
2. Find and manage your iTunes backups - Apple Support
3. How to back up your devices using iCloud or iTunes - Apple Support
4. If you can't make an iTunes backup of your iPhone, iPad, or iPod touch - Apple Support
5. http://www.wikihow.com/Back-Up-Your-iPhone
6. Most commonly used backup methods

Follow Up Question: More generally, do most types of new backups typically replace (and delete) old backups? ...iCloud backups? ...TimeMachine?