An Interior Locution is a private revelation heard or received internally, which we must verify before determining any recognition or significance.
The Catechism of the Catholic Church (CCC) explains:
The Church has recognized some private revelations, though it is not private revelations’ role to improve or complete Christ’s Revelation.
The Church’s sensus fidelium knows how to discern and welcome in these revelations whatever constitutes an authentic call of Christ or his saints. Christian faith cannot accept “revelations” that claim to surpass or correct the Revelation of which Christ is the fulfillment, as it is the case in certain non-Christian religions and also in certain recent sects which base themselves on such “revelations.” (CCC 67)
I had one Interior Locution from the Father, four from Christ, many from the Holy Spirit, and one from the Blessed Mother. The messages were short, clear and proactive.
The Holy Spirit asked me in early 2022 through an Interior Locution to write in Filipino to the Philippines.