Input Group

<div class="input-group mb-3">
    <div class="input-group-prepend">
        <span class="input-group-text" id="basic-addon1">@</span>
    </div>
    <input type="text" class="form-control" placeholder="Username" aria-label="Username" aria-describedby="basic-addon1">
</div>

<div class="input-group mb-3">
    <input type="text" class="form-control" placeholder="Recipient's username" aria-label="Recipient's username" aria-describedby="basic-addon2">
    <div class="input-group-append">
        <span class="input-group-text" id="basic-addon2">@example.com</span>
    </div>
</div>

<label for="basic-url">Your vanity URL</label>
<div class="input-group mb-3">
    <div class="input-group-prepend">
        <span class="input-group-text" id="basic-addon3">https://example.com/users/</span>
    </div>
    <input type="text" class="form-control" id="basic-url" aria-describedby="basic-addon3">
</div>

<div class="input-group mb-3">
    <div class="input-group-prepend">
        <span class="input-group-text">$</span>
    </div>
    <input type="text" class="form-control" aria-label="Amount (to the nearest dollar)">
    <div class="input-group-append">
        <span class="input-group-text">.00</span>
    </div>
</div>

<div class="input-group">
    <div class="input-group-prepend">
        <span class="input-group-text">With textarea</span>
    </div>
    <textarea class="form-control" aria-label="With textarea"></textarea>
</div>
                                    

<div class="input-group mb-3">
    <div class="input-group-prepend">
        <button class="btn btn-outline-secondary" type="button" id="button-addon1">Button</button>
    </div>
    <input type="text" class="form-control" placeholder="" aria-label="Example text with button addon" aria-describedby="button-addon1">
</div>

<div class="input-group mb-3">
    <input type="text" class="form-control" placeholder="Recipient's username" aria-label="Recipient's username" aria-describedby="button-addon2">
    <div class="input-group-append">
        <button class="btn btn-outline-secondary" type="button" id="button-addon2">Button</button>
    </div>
</div>

<div class="input-group mb-3">
    <div class="input-group-prepend" id="button-addon3">
        <button class="btn btn-outline-secondary" type="button">Button</button>
        <button class="btn btn-outline-secondary" type="button">Button</button>
    </div>
    <input type="text" class="form-control" placeholder="" aria-label="Example text with two button addons" aria-describedby="button-addon3">
</div>

<div class="input-group">
    <input type="text" class="form-control" placeholder="Recipient's username" aria-label="Recipient's username with two button addons" aria-describedby="button-addon4">
    <div class="input-group-append" id="button-addon4">
        <button class="btn btn-outline-secondary" type="button">Button</button>
        <button class="btn btn-outline-secondary" type="button">Button</button>
    </div>
</div>