An email-signature is basically a set of text which is attached to the end of an email you wish to send. Generally, a signature comprises information such as Sender’s Name, Email Address, Business Contact Information, or Web Site URL.
Using Signature in the emails make them look more sophisticated to the recipient. If you are using Yahoo Mail, you can easily configure your account to automatically add a signature to the email messages each time you send an email to a recipient. You can add anything from logos, images, texts to business cards or photos of your signature to the outgoing email message.