Sola scriptura is a Latin phrase meaning “by Scripture alone," a foundational doctrine of the Protestant Reformation asserting that the Bible is the highest and final authority on all matters of faith and practice. It teaches that Scripture, as God's divinely inspired and sufficient Word, contains all truth necessary for salvation and spiritual life, and should be the ultimate standard by which all other teachings and traditions are judged. 

Key Aspects of Sola Scriptura:

• Supreme Authority: Scripture holds the ultimate authority within the Christian faith. 

• Sufficiency: The Bible is considered sufficient to provide all the necessary teaching for salvation and a life of faith. 

• Divine Revelation: Scripture is understood as a direct revelation from God, a trustworthy source of truth. 

• Infallibility: The Bible is considered to be without error, making it the infallible rule for the church and for Christian life. 

What Sola Scriptura is Not:

• Excluding all human knowledge: It doesn't claim that all truth of every kind is in Scripture, only the truth needed for spiritual matters and salvation. 

• Negating human reason or experience: While Scripture holds supreme authority, it doesn't forbid the use of reason or the value of personal experience; rather, these are evaluated under the authority of the Bible. 

In essence, sola scriptura refers to the Bible as the definitive source of spiritual truth and a critical standard for evaluating all other claims to authority, such as traditions or human interpretations, and can serve as a principle for resolving religious controversies by establishing scriptural authority.