&reftitle.required; As of version 1.8.0, the driver requires PHP 7.0 or higher. Previous versions of the driver allow compatibility with older PHP versions. The driver requires libbson and libmongoc, and will use bundled versions of both libraries by default. System libraries may also be used, as discussed in the manual installation documentation. The driver, via libmongoc, optionally depends on a TLS library (e.g. OpenSSL) and will use it if available. If the build process fails to find a TLS library, users should check that the appropriate development package (e.g. libssl-dev) and pkg-config are both installed. The process for detecting and configuring TLS libraries is discussed in more detail in the manual installation documentation. Cyrus SASL is an optional dependency to support Kerberos authentication and will be used if available. Due to potential problems representing 64-bit integers on 32-bit platforms, users are advised to use 64-bit environments. When using a 32-bit platform, be aware that any 64-bit integer read from the database will be returned as a MongoDB\BSON\Int64 instance instead of a PHP integer type.