recommended cipher
In the above example AES_128_GCM forms the cipher. AES is the preferred algorithm and using a key size of 128bits is acceptable. You can prefer 128bit keys over 256bit keys for performance reasons. The GCM segment is the mode of the cipher and indicates that this is an AEAD (Authenticated Encryption with Associated Data). GCM suites should be prioritised over non GCM suites. An example with the GCM and non-GCM versions of the same suite.
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_RSA_WITH_AES_128_SHA256
TLS_ECDHE_RSA_WITH_AES_256_SHA384