No matter how knowledgeable or experienced you are in your field, poor writing can damage your credibility and make it difficult to communicate ideas to your audience. Mixing up verb tenses, for example, can distract readers and confuse your message. Tenses indicate when a verb's action takes place, and are classified according to three basic forms: simple, progressive and perfect. Keep your writing clear and intelligible by learning to use English grammar rules on tenses.

Simple Tenses

Use these tenses to indicate relatively simple time relations. The simple tenses include present tense, past tense and future tense. For the verb "to write," the simple present tense is used for actions occurring at the present time or for actions that occur on a regular basis. For example, "She writes a letter" or "She writes every morning." The simple past tense is used for actions completed in the past; "She wrote a letter." The simple future tense is used for actions that will occur in the future; "She will write a letter."

The simple present tense should also be used when writing about action in a literary work (for example, write "Jane Eyre finally comes to realize the mysteries of the estate" instead of "Jane Eyre finally came to realize the mystery of the household"), and when quoting or summarizing a work (for example, use "In his essay, Grant argues that Jane Eyre marks the peak of Victorian literature" instead of "In his essay, Grant argued that Jane Eyre marked the peak of Victorian Literature").

Progressive Tenses

Progressive tense forms express continuing actions. Use the present, past and future progressive tenses to indicate ongoing actions. For example, the verb "to write" in the present progressive form is "she is writing." The past progressive form of this verb is "she was writing." The future progressive form is "she will be writing."

Perfect Tenses

Perfect tenses indicate slightly more complex time relations and are generally used to express completed actions. For the verb "to write," the present perfect tense is "she has written." The past perfect tense is "she had written." The future perfect tense is "she will have written."

There is also a form of the perfect tense known as the perfect progressive, which expresses actions that continue up to some point in the present, past or future. For example, the present perfect progressive is "she has been writing." The past perfect progressive is "she had been writing." The future perfect progressive is "she will have been writing."