Yes, CDs can be signed. Optical discs are usually made of plastic material with a writable surface, which allows us to sign on the surface with a special oily pen or a permanent marker. There are many reasons for signing a CD, such as:

1. Commemorative value: For music CDs, movie DVDs or other special CDs, signature can increase their commemorative value. When we get a signed CD, it will become a precious collection, representing a direct connection with an artist or celebrity.

2. Personalization: Signing a CD can also be a way of personalization. For example, we can buy CDs of our favorite musicians or actors and sign them in person, so that we have a unique customized CD.

3. Give gifts: Signed CDs can also be used as unique gifts for friends, family or fans. Such a gift has a special meaning and can express our love and concern for each other.

It should be noted that signing a CD may affect its readability and service life. Therefore, before signing the CD, it is best to ensure that the signing tools used are safe and will not scratch or damage the surface of the CD. In addition, the signed CD should be properly kept to avoid scratches or exposure, so as to maintain its quality and readability.

In a word, CDs can be signed, which gives us more choices of personalization and commemorative value.