not really a question but this is more of a tip

Here is a list of Mac computers that support macOS Mojave:

• MacBook (Early 2015 or newer)
• MacBook Air (Mid 2012 or newer)
• MacBook Pro (Mid 2012 or newer)
• Mac mini (Late 2012 or newer)
• iMac (Late 2012 or newer)
• iMac Pro (2017)
• Mac Pro (Late 2013, plus mid-2010 and mid-2012 models with recommended Metal-capable GPU)

Here is a list of Mac computers that support macOS High Sierra:

• MacBook (Late 2009 or newer)
• MacBook Pro (Mid 2010 or newer)
• MacBook Air (Late 2010 or newer)
• Mac mini (Mid 2010 or newer)
• iMac (Late 2009 or newer)
• Mac Pro (Mid 2010 or newer)

macOS Sierra : same as High Sierra

Here is a list of Mac computers that support OS X Yosemite:

• iMac (Mid-2007 or newer)
• MacBook (Late 2008 Aluminum, Early 2009 or newer)
• MacBook Pro (Mid/Late 2007 or newer)
• MacBook Air (Late 2008 or newer)
• Mac mini (Early 2009 or newer)
• Mac Pro (Early 2008 or newer)

OS X El Capitan : same as OS X Yosemite