The account_login.twig view hosts the page where a registered customer logs into their account.
Account login form
Registered customers log into their account using the account login form.
It's best practice to include a quick and easy link that the customer can use to request a new password if they have forgotten their existing one, e.g.
<a href="/account/forgotten-password">forgotten your password? click here</a>
A 'remember me' tick box can be included within the login form to keep the customer logged into their account. The field name is remember, e.g.
<input type="checkbox" name="remember" value="1">Keep me logged in