If you've landed on usa864.sfdc-8tgtt5.salesforce.com, you're looking at a standard Salesforce login page. The URL is a subdomain of salesforce.com, so the identity is clear: this is Salesforce's platform, not a copycat. The security is well above what you'd expect from a scam site: modern encryption, clickjacking protection, and enforced HTTPS all in place. Salesforce customer instances often use auto-generated subdomains like this one, so the odd string is normal.
What to watch for: Always verify that the domain ends in salesforce.com before typing your password. Phishing attempts often use misspellings like 'salesforcee.com' or 'saleforce.com'. Here, the parent domain is genuine. The site also has a privacy policy and terms of service, which is a good sign for a service handling your data. If you're a Salesforce customer using this specific instance, it's safe to log in. If you're unsure, check with your company's IT team which Salesforce domain they use.