Generally, yoga shoes are not necessary during yoga sessions. Most yoga sessions are practiced barefoot or in socks to maintain a good grip and balance on the mat. Wearing shoes can also hinder the flexibility and range of motion required for many yoga poses.

However, there are some types of yoga shoes designed specifically for yoga that can be used during practice. These shoes are usually lightweight and have a thin, flexible sole to allow for proper foot movement and balance. They can be helpful for people who prefer to wear shoes or have issues with their feet, such as plantar fasciitis.
In general, it's best to check with your yoga instructor or studio before wearing shoes to a class to see if they allow it or if there are specific types of shoes that are recommended.