Along with 1 and 2 Timothy, Titus is the third of the Pastoral Epistles. Titus is the recipient and the author generally considered to be someone other than Paul. (See the introduction to 1 Timothy for more information about the authorship of the Pastoral Epistles.)
Titus 1:5 mentions that Paul and Titus had been together in Crete, which is not mentioned in the book of Acts. Titus was left there to continue the work and to appoint elders in the towns. This gives the author occasion to instruct his readers on various topics.
Elders (or overseers/bishops) are needed to maintain sound doctrine in the churches, and these people must be of impeccable character. Cretans apparently had a bad reputation (see 1:12), and so they were in need of sharp rebuke and correction.
Sound doctrine, however, is not simply a list of things to believe. This letter lays out that doctrine is invariably connected to upright behavior. Older men are to be temperate; older woman are to be reverent and teach younger woman to love their husbands and children; young men are to be self-controlled; slaves are to be subject to their masters in order to make the gospel attractive to outsiders. The people are also reminded to be subject to church authorities and avoid foolish controversies over fine points of the law.
Among the shorter books of the New Testament (forty-six verses), Titus is a glimpse into the structure and values of the early church. The emphasis on self-control and temperance in chapter 2 is reminiscent of wisdom teaching in the Old Testament.
– Peter Enns