In computer networking, a reliable protocol provides reliability properties with respect to the delivery of data to the intended recipient(s), as opposed to an unreliable protocol, which does not provide notifications to the sender as to the delivery of transmitted data. The term "reliable" is a synonym for assured, which is the term used by the ITU and ATM Forum in the context of the ATM Service-Specific Coordination Function, for example for transparent assured delivery with AAL5.
Reliable protocols typically incur more overhead than unreliable protocols, and as a result, function more slowly and with less scalability. This often is not an issue for unicast protocols, but it may become a problem for reliable multicast protocols.
TCP, the main protocol used on the Internet, is a reliable unicast protocol. UDP, often used in computer games or in other situations where speed is an issue and the loss of a little data is not as important because of the transitory nature of the data, is an unreliable protocol.
John Wesley believed that all Christians have a faith which implies an assurance of God's forgiving love, and that one would feel that assurance, or the "witness of the Spirit". This understanding is grounded in Paul's affirmation, "...ye have received the Spirit of adoption, whereby we cry Abba, Father. The same Spirit beareth witness with our spirits, that we are the children of God..." (Romans 8:15-16, Wesley's translation). This experience was mirrored for Wesley in his Aldersgate experience wherein he "knew" he was loved by God and that his sins were forgiven.