Providing username and password to a website to prove your identity to access personalized or protected content or service, is called Sign In. The provided username and password are set up at the time of registration. Most websites allow you to use email as a username while others require you to choose a specific username (other than email) with password.
In modern times, people use many services for their online needs. Some services are required for professional work while others for personal needs. For example, services like Gmail, YouTube, Facebook, Amazon, Slack, Dropbox, WhatsApp are some of the most common that most people use. If you use the same email and password combination on all websites, it means if one website's credentials are compromised, you would lose access to all accounts (with one exception i.e. when 2-Factor authentication is not set, it's explained below). The best strategy seems to be to have one email but to set different passwords on each website.
If you use different passwords for each website, it means you are more likely to forget the password. The possibility increases as many online services require you to change the password periodically. When we try to recover a forgotten password, most websites send a link to reset password as email to our provided email address. It follows two things, first you should be more vigilant to setup and remember the email account password. Second, you must choose an email provider that provides high security, has a professional team and service. For example choosing Gmail.com is much better as compared to choosing the email service provided by your website hosting provider (for example).
If the website you are using is complex or its User Interface (UI) is not optimized as per modern and standard practices, you may face difficulty to locate its Sign In page. In the same way, you may face an issue during Sign In. For such issues, the best way to save your time is, enter the website name followed by a "Sign In Link" or “Sign In Troubleshooting” in Google search engine. By this, google.com shall display the links to websites that provide help to Troubleshoot Sign In Issues (like signin-link.com) or direct link of the Sign In page of the website you are looking for.
signinlink.com [at] gmail [dot] com