NFC (Near Field Communication) tags are generally considered safe to use, but there are several factors to keep in mind regarding their security:

1. Limited Range: 

NFC technology operates at short distances, typically within a few centimeters. This limited range reduces the risk of unauthorized access compared to other wireless technologies.

2. Encryption: 

Many NFC tags support encryption, which helps protect the data stored on them during transmission. However, not all NFC tags come with built-in encryption, so it's important to choose the right type if security is a concern.

3. Data Overwrite and Protection: 

Some NFC tags allow for write protection or can be locked after being written to, preventing further changes. This feature is useful for ensuring the integrity of the data.

4. Potential Vulnerabilities: 

Like any technology, NFC is not immune to security vulnerabilities. For example, if an NFC tag contains sensitive information (like personal data or payment details), it could be read by someone with a compatible NFC reader if they get too close.

5. Malicious Tags: 

There is a risk of malicious NFC tags being placed in public spaces, which could direct users to phishing sites or install unwanted applications. Users should be cautious about scanning unknown tags.

6. Device Security: 

The overall safety of using NFC tags also depends on the security measures implemented on the smartphone or device being used. Keeping software updated, using antivirus programs, and avoiding suspicious applications can enhance safety.

In summary, while NFC tags can be safe when used properly, it's essential to consider the potential risks and take appropriate precautions, such as being cautious about unknown tags and ensuring your devices have adequate security measures.