The name Ger (stranger) has come to mean in Hebrew a convert to Judaism who performs the duties and enjoys the privileges of a Jew. Anyone who has accepted Judaism out of inner convition and without ulterior motives is called a Ger Tzaddik (a sincere, true proselyte).
There is a 'partial' proselyte, referred to as a Ger Toshav (a sojourning proselyte), who has not adopted Judaism in its entirety, but has agreed to observe the Seven Precepts imposed upon the descendants of Noach:
"If one sincerely wishes to adopt Judaism, welcome and befriend him; do not repel him" (Yevamot 47b, 109b; Mechilta 18:6).
"If one comes to ask for admission to Yisrael, he is not received at once, but is asked: 'Do you not know that this nation is downtrodden and afflicted, subjected to many ills, liable to varied penalties for disobedience to the precepts of Torah?... If he persists, he takes a ritual bath and submits to circumcision." (Yevamot 47a)
Both male and female applicants become proselytes by Tevilah (immersion) in a mikveh or pool of running water. Upon emerging from the water they pronounce this blessing:
"Blessed are You, Hashem our G-d, King of the universe who has sanctified us with Your commandments, and commanded us about immersion."
The reason that proselytes recite this blessing AFTER the immersion, and not before the performance of this precept, is that prior to the immersion it does not apply to them.
To be kasher (fit for use), water of the mikveh has to come directly from a natural spring or a river.
According to Rabbinic teaching, any person who regulates his life by the Seven Precepts of the descendants of Noach fulfils his immediate task as a co-worker with G-d. But higher in character must b e the contribution of the son of Yisrael, who is charged with the duty to promote divine righteousness on earth. Jews must be thoroughly obedient to the Torah in which is revealed the moral will of G-d.