What is the primary purpose of using a self-signed certificate?

The primary purpose of using a self-signed certificate is indeed to provide SSL functionality in temporary test or development servers. Self-signed certificates are often utilized in environments where security needs are less stringent, such as during the development or testing phases. These environments do not typically require the same level of trust that is necessary in production settings.

By using a self-signed certificate, developers can easily secure communication between servers and clients without the necessity of acquiring a certificate from a Certificate Authority (CA). This is particularly useful in development and testing setups where costs and administrative overhead can be reduced, as developers can generate and manage such certificates internally.

In production environments, it is generally recommended to use CA-signed certificates to ensure that clients can trust the server, since self-signed certificates will not be recognized as valid by default. This makes them unsuitable for public-facing or production systems where trust and security are paramount. Thus, while self-signed certificates can be valuable for development purposes, their use in production or public servers is discouraged.