The verb "let" is an irregular verb in English, meaning to allow or permit something to happen. Its conjugation is unique and does not follow the regular pattern of adding "-ed" for past forms.

In the present simple tense, "let" remains in its base form for all subjects: "I let," "you let," "he/she/it lets," and so on. For example, "She lets her children play outside."

In the past simple tense, "let" remains "let." This form is used to talk about actions of allowing or permitting that were completed in the past. For instance, "He let me borrow his bike yesterday."

The past participle of "let" is also "let." When forming perfect tenses, such as the present perfect or past perfect, the past participle is combined with auxiliary verbs. An example sentence is "They have let their dog roam freely."

"Let" is typically used as a transitive verb, meaning it requires a direct object to complete its meaning: "She let him enter the room."

The verb "let" is often used in various expressions and phrases, such as "let go" (to release), "let down" (to disappoint), and "let in" (to allow someone to enter).

Understanding the irregular conjugation of "let" is crucial for accurately describing actions of allowing or permitting. Its versatility and frequent use in idiomatic expressions make it an important verb in the English language.