diff --git a/app/javascript/mastodon/features/compose/components/search.js b/app/javascript/mastodon/features/compose/components/search.js
index 85ef767ab..79abffad8 100644
--- a/app/javascript/mastodon/features/compose/components/search.js
+++ b/app/javascript/mastodon/features/compose/components/search.js
@@ -1,11 +1,46 @@
 import React from 'react';
 import PropTypes from 'prop-types';
-import { defineMessages, injectIntl } from 'react-intl';
+import { defineMessages, injectIntl, FormattedMessage } from 'react-intl';
+import { Overlay } from 'react-overlays';
+import { Motion, spring } from 'react-motion';
 
 const messages = defineMessages({
   placeholder: { id: 'search.placeholder', defaultMessage: 'Search' },
 });
 
+class SearchPopout extends React.PureComponent {
+
+  static propTypes = {
+    style: PropTypes.object,
+  };
+
+  render () {
+    const { style } = this.props;
+
+    return (
+      <div style={{ ...style, position: 'absolute', width: 285 }}>
+        <Motion defaultStyle={{ opacity: 0, scaleX: 0.85, scaleY: 0.75 }} style={{ opacity: spring(1, { damping: 35, stiffness: 400 }), scaleX: spring(1, { damping: 35, stiffness: 400 }), scaleY: spring(1, { damping: 35, stiffness: 400 }) }}>
+          {({ opacity, scaleX, scaleY }) => (
+            <div className='search-popout' style={{ opacity: opacity, transform: `scale(${scaleX}, ${scaleY})` }}>
+              <h4><FormattedMessage id='search_popout.search_format' defaultMessage='Advanced search format' /></h4>
+
+              <ul>
+                <li><em>#example</em> <FormattedMessage id='search_popout.tips.hashtag' defaultMessage='hashtag' /></li>
+                <li><em>@username@domain</em> <FormattedMessage id='search_popout.tips.user' defaultMessage='user' /></li>
+                <li><em>URL</em> <FormattedMessage id='search_popout.tips.user' defaultMessage='user' /></li>
+                <li><em>URL</em> <FormattedMessage id='search_popout.tips.status' defaultMessage='status' /></li>
+              </ul>
+
+              <FormattedMessage id='search_popout.tips.text' defaultMessage='Simple text returns matching display names, usernames and hashtags' />
+            </div>
+          )}
+        </Motion>
+      </div>
+    );
+  }
+
+}
+
 @injectIntl
 export default class Search extends React.PureComponent {
 
@@ -19,6 +54,10 @@ export default class Search extends React.PureComponent {
     intl: PropTypes.object.isRequired,
   };
 
+  state = {
+    expanded: false,
+  };
+
   handleChange = (e) => {
     this.props.onChange(e.target.value);
   }
@@ -43,11 +82,17 @@ export default class Search extends React.PureComponent {
   }
 
   handleFocus = () => {
+    this.setState({ expanded: true });
     this.props.onShow();
   }
 
+  handleBlur = () => {
+    this.setState({ expanded: false });
+  }
+
   render () {
     const { intl, value, submitted } = this.props;
+    const { expanded } = this.state;
     const hasValue = value.length > 0 || submitted;
 
     return (
@@ -62,6 +107,7 @@ export default class Search extends React.PureComponent {
             onChange={this.handleChange}
             onKeyUp={this.handleKeyDown}
             onFocus={this.handleFocus}
+            onBlur={this.handleBlur}
           />
         </label>
 
@@ -69,6 +115,10 @@ export default class Search extends React.PureComponent {
           <i className={`fa fa-search ${hasValue ? '' : 'active'}`} />
           <i aria-label={intl.formatMessage(messages.placeholder)} className={`fa fa-times-circle ${hasValue ? 'active' : ''}`} />
         </div>
+
+        <Overlay show={expanded && !hasValue} placement='bottom' target={this}>
+          <SearchPopout />
+        </Overlay>
       </div>
     );
   }
diff --git a/app/javascript/styles/components.scss b/app/javascript/styles/components.scss
index 48d6e0c4d..e83a22e00 100644
--- a/app/javascript/styles/components.scss
+++ b/app/javascript/styles/components.scss
@@ -4063,6 +4063,37 @@ button.icon-button.active i.fa-retweet {
   border-radius: 0;
 }
 
+.search-popout {
+  background: $simple-background-color;
+  border-radius: 4px;
+  padding: 10px 14px;
+  padding-bottom: 14px;
+  margin-top: 10px;
+  color: $ui-primary-color;
+  box-shadow: 2px 4px 15px rgba($base-shadow-color, 0.4);
+
+  h4 {
+    text-transform: uppercase;
+    color: $ui-primary-color;
+    font-size: 13px;
+    font-weight: 500;
+    margin-bottom: 10px;
+  }
+
+  li {
+    padding: 4px 0;
+  }
+
+  ul {
+    margin-bottom: 10px;
+  }
+
+  em {
+    font-weight: 500;
+    color: $ui-base-color;
+  }
+}
+
 noscript {
   text-align: center;