Share of Wallet or competitor analysis
The native feature is “Competitors” as @Eric Grubaugh mentioned. Check out:
“Competitors” SuiteAnswer Id: 9622
“Using Opportunities” SuiteAnswer Id: 9617
“Opportunity Reports” SuiteAnswer Id: 9611
It’s basically just another entity record that you can record to know who you were competing against on opportunities, who won/lost, and maybe enter some details/information on why. If you want more you could either build something yourself or look for SuiteApps/SuiteBundles that someone else has already built.