Subscriber trunk dialling (STD, also known as subscriber toll dialing) is a telephone system allowing subscribers to dial trunk calls without operator assistance. The term was introduced when it first became possible for long-distance calls to be dialed directly, and is now rarely used where calls to any destination can be dialed.
Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs), are infections that are commonly spread by sexual activity, especially vaginal intercourse, anal sex and oral sex.
Symptoms and signs of the STDs
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